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MARINE TURTLE FISHERY OF CARIBBEAN NICARAGUA: 
HUMAN USE PATTERNS AND HARVEST TRENDS 



By 

CYNTHIA JEAN LAGUEUX 









A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL 

OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT 

OF THE REQUIREMENTS FOR THE DEGREE OF 

DOCTOR OF PHILOSOPHY 

UNIVERSITY OF FLORIDA 

1998 



ACKNOWLEDGMENTS 

I could not have completed this dissertation without the technical assistance, 
financial and emotional support of numerous people throughout these many years. With 
deep appreciation and respect, I thank the members of my doctoral committee, Kent 
Redford (Chair), Lou Guillette (acting Co-Chair), Jeanne Mortimer, Richard Bodmer, 
George Tanner, and Lyn Branch. I am honored to have the opportunity to know and 
work with each of them and I thank them for their inspiration, leadership, and support. A 
special thank you to J. Mortimer for her tireless effort in improving my writing skills. 

I would like to extend my sincerest appreciation to the people of the Caribbean 
coast of Nicaragua who allowed me into their lives, if only for a short period, and without 
whose cooperation and trust this study would not have been possible. I especially thank 
the people of the communities of Awastara, Dakra, Rio Grande Bar, Sandy Bay, Sandy 
Bay Sirpi, Set Net, and Tasbapaune for their friendliness, patience, and generosity in 
sharing their knowledge, food, and homes with me. 

I am indebted to the marine turtle butchers of Puerto Cabezas: Cecil Clark, 
Winston Martinez, Cristina Ramos, Carolina Guillermo, David Kingsman, Nora Pablo, 
Idincio Kingsman, Norma, Justis, Clasida, Aaron, Tano Chow, Marcia Hammer, Jack 
Morris, Victoria Flores, Ilario Flores, Virginia and Stanford Humphries, Rosa and Raisil 
Wilson, Sam Peralta, Norma Blair, Rina Ramos, Martin Martinez, Alberto Renales, and 

ii 



Mejia. Night after night, they allowed me to measure and weigh their animals, and I am 
grateful for their patience as I removed tissue samples while they butchered them. I am 
especially thankful to have worked along side Cecil Clark, Alejandro Clark (Julio), and 
Winston Martinez, who, with their many years of experience, skill, and knowledge, 
taught me much about marine turtles and their anatomy. 

I appreciate the dedication and hard work of the numerous community data 
collectors. In many aspects, the success of this study and the strength of the conclusions 
are based on their hard work, dedication, and conscientious manner in which they 
collected the harvest data. I thank each of them: Rodrigo Renales, Eupreciano 
Hoppington, and Orlando Grantt of Awastara; Aida Morris and Ermicinda Pong of 
Dakra; Waldemar Brooks, Silvio Perera, and Guillermo Recta of Sandy Bay; Ejan Smith, 
Emelina Smith, and Stanley Martinez of Sandy Bay Sirpi, Lorna Churnside of Rio 
Grande Bar; Riley Carlos and Olivia Wilson of Tasbapaune; Francela Thomas of Set Net; 
Joseph Humphries (Haulover) of Corn Island; and Cecil Clark, Julio Clark, Winston 
Martinez, and Denis Castro of Puerto Cabezas. I especially would like to acknowledge 
the work of Ejan Smith with whom I enjoyed many visits and conversations about sea 
turtles. Ejan was lost at sea in December 1996, he is painfully missed. 

I also thank Denis Castro for the many hours we have spent discussing the use and 
conservation of natural resources on the Caribbean coast of Nicaragua, for his hard work, 
his collaboration during the many weeks we have spent visiting communities along the 
Nicaragua coast, and for sharing with me insight into his culture. I appreciate the 



111 



expertise of D. Castro for translating my dissertation abstract into Miskitu and Olga 
Montenegro for translating it into Spanish. 

I would like to acknowledge the many friends I made while living in Puerto 
Cabezas with whom I shared cold beers, softball and baseball games, and I thank them 
for their concern and care when I became ill. In particular, I thank Flor Francis, Lilia and 
Nelbert Taylor, Berit Stokstad, Enrique and Erlinda Obregon, Ricky Newball, and Ana 
Peachy for making my experiences in Puerto Cabezas memorable. 

I am grateful to my very dear friends in Managua, Dona Tulita Garcia, Carmen 
Labro, and Carmen Irene and Alejandrina (Alex) Hildeprandt for opening up their home 
to me. They always welcomed me with good home cooking and a place to relax. I 
appreciate their patience even when I filled up their home with many trunks of equipment 
and supplies each time I entered the country and with the same number of trunks filled 
with turtle bones, blood, urine, feces, and reproductive tracts each time I exited the 
country. 

There have been several key people throughout the years whose technical 
knowledge and skills were crucial in the completion of my dissertation: I would like to 
thank my very own personal computer guru, Noel Ocampo, who, for the price of 
chocolate, kept my computer up and running; Howard Kochman, my SAS mentor, for 
sharing his priceless knowledge of SAS and ANCOVA's; Tim Gross for assisting me in 
purchasing supplies and equipment; Cathy Cox, Andy Rooney, and Drew Crain for 
teaching me histological methods; and Jay Harrison and Scott Kowalski of the Institute of 
Food and Agriculture Sciences, University of Florida, for their statistical consultations. 



IV 



A special thank you to Cathi Campbell for assisting me with collecting turtle 
samples, conducting statistical analyses, writing SAS programs, solving computer 
software quirks, and editing drafts of the dissertation. I am also thankful to her for the 
innumerable discussions about sea turtle ecology, human use of natural resources, and 
conservation biology that we have had. 

Numerous personnel of the Servicio de Areas Silvestres y Fauna, Ministerio del 
Ambiente y Recursos Naturales (MARENA), Managua assisted me in obtaining research 
permits. Staff of the CITES (Convention on International Trade in Endangered Species 
of Wild Fauna and Flora) office in Managua and Washington D.C. were always helpful 
and prompt in assisting me to obtain export and import permits. I am grateful to Cecil 
Clark of Puerto Cabezas, Nicaragua; the Centro de Investigaciones y Documentation de 
la Costa Atlantica, Bluefields, Nicaragua; and the Caribbean Conservation Corporation, 
Gainesville, Florida for providing me with their unpublished harvest data. 

I am indebted to the following organizations without whose financial support this 
study would have remained only an idea: Wildlife Conservation Society, Inter-American 
Foundation, Chelonian Foundation, The Nature Conservancy, Sigma Xi, Caribbean 
Conservation Corporation, and the U.S. Agency for International Development. 

I am very grateful to my mother, Lillian Minarik, who has always believed in me 
and has been financially and emotionally supportive through all my endeavors. 
Regardless of the project, she has always been interested in what I was doing and willing 
to jump in and assist, from conducting necropsies on decomposing marine turtle carcasses 
to assisting throughout the night with the collection of turtle blood, urine, feces, and 



reproductive tracts. Her assistance in data entry and proofing were invaluable. I also 
thank my father, Robert Minarik, for his financial support during the writing of the 
dissertation. 

And finally, I thank my friends and colleagues for their stimulating conversation 
and support. Over the years, I have come to realize that I could not have attempted nor 
completed this degree alone and my accomplishment is a tribute to everyone who 
believed in me. Without all of the many components coming together at the right time 
and place the dissertation which you are about to read would not be in front of you. 






VI 



TABLE OF CONTENTS 

ACKNOWLEDGMENTS ii 

ABSTRACT x 

RESUMEN xii 

KLUTKA xiv 

CHAPTERS 

1 INTRODUCTION 1 

Sea Turtles as a Resource 1 

Worldwide Status of Sea Turtles 2 

Historical Harvest of Sea Turtles, Except Nicaragua 3 

Historical Harvest of Sea Turtles from Caribbean Waters of Nicaragua . 20 
Marine Turtles and the Nicaragua Fishery 23 

2 HUMAN USE PATTERNS 27 

Introduction 27 

Methods 31 

Results 39 

Discussion 54 

Conclusions 64 

3 HARVEST RATES AND DEMOGRAPHICS OF MARINE TURTLES ... 66 

Introduction 66 

Methods 69 

Results 77 

Discussion 96 

Conclusions Ill 



VII 



4 REPRODUCTIVE CHARACTERISTICS AND CYCLICITY OF GREEN 
TURTLES ON A FORAGING GROUND 113 

Introduction 113 

Methods 115 

Results 120 

Discussion 135 

Conclusions 142 

5 ASSESSMENT OF HARVEST LEVELS AND THEIR IMPACT ON 
MARINE TURTLE POPULATIONS 144 

Introduction 144 

Methods 148 

Results 149 

Discussion 150 

Conclusions 160 

6 MANAGEMENT IMPLICATIONS, RECOMMENDATIONS, AND 
RESEARCH NEEDS 162 

Implications for Managing the Marine Turtle Fishery 162 

Management Recommendations 167 

Recommendations for Future Research 171 



APPENDICES 



A MINIMUM NUMBER AND (PERCENT) OF MARINE TURTLES 
CAPTURED IN THE REGION AUTONOMA DEL ATLANTICO 
NORTE, NICARAGUA FOR THE PERIODS FEBRUARY 1994 TO 
JANUARY 1995 AND DECEMBER 1995 TO APRIL 1997 173 

B MINIMUM NUMBER OF MARINE TURTLES CAPTURED BY 
COMMUNITY IN THE REGION AUTONOMA DEL ATLANTICO 
SUR, NICARAGUA 176 

C MINIMUM NUMBER OF GREEN TURTLES, CHELONIA MYDAS, 
LANDED AT EACH SITE ON THE CARIBBEAN COAST OF 
NICARAGUA FROM 1991 TO 1996 182 

D PEARSON CORRELATION COEFFICIENTS FOR TEN BODY 
MEASUREMENTS OF GREEN TURTLES, CHELONIA MYDAS, 
HARVESTED FROM THE CARIBBEAN WATERS OF NICARAGUA .185 

viii 



E REGRESSION ANALYSIS OF CURVED CARAPACE LENGTH 
(CLN) AGAINST NINE OTHER BODY MEASUREMENTS OF 
HARVESTED GREEN TURTLES, CHELONIA MYDAS, BY SEX 
FROM THE CARIBBEAN WATERS OF NICARAGUA 186 

F MINIMUM NUMBER OF HAWKSBILL, ERETMOCHEL YS 
IMBRICATA; LOGGERHEAD, CARETTA CARETTA; AND 
LEATHERBACK, DERMOCHELYS CORIACEA, TURTLES 
REPORTED CAPTURED AND/OR HARVESTED IN THE 
CARIBBEAN WATERS OF NICARAGUA FROM 1991 TO 1996 187 

G SUMMARY STATISTICS OF BODY SIZE PARAMETERS FOR 
HARVESTED HAWKSBILL, ERETMOCHELYS IMBRICATA, 
TURTLES 188 

LITERATURE CITED 189 

BIOGRAPHICAL SKETCH 214 



ix 



Abstract of Dissertation Presented to the Graduate School 

of the University of Florida in Partial Fulfillment of the 

Requirements for the Degree of Doctor of Philosophy 

MARINE TURTLE FISHERY OF CARIBBEAN NICARAGUA: 
HUMAN USE PATTERNS AND HARVEST TRENDS 

By 

Cynthia Jean Lagueux 

May 1998 

Chairperson: Kent H. Redford, Ph.D. 

Major Department: Wildlife Ecology and Conservation 

The Miskitu Indian marine turtle fishery of Caribbean Nicaragua was studied to 
determine human use patterns and harvest trends in the fishery, and to evaluate its impact 
on marine turtle populations. Specific objectives of the study were to 1) characterize 
human use patterns, 2) quantify the number of animals harvested annually, 3) describe the 
size and sex of harvested animals, 4) describe the reproductive cycle of green turtles 
(Chelonia mydas), 5) evaluate the impact of the fishery on marine turtle populations, and 
6) provide management and research recommendations. 

Green turtles are targeted in the fishery, hawksbills (Eretmochelys imbricata) are 
harvested opportunistically, and loggerheads {Caretta caretta) and leatherbacks 
(Dermochelys coriacea) are captured incidentally in nets set for green turtles. Marine 
turtles are a source of protein, provide income through the sale of meat and tortoiseshell, 



and most recently, used as bait in other fisheries. Current minimum annual harvest levels 
of green turtles are 10,000 to 1 1,000 animals, levels that are as high or higher than they 
have probably ever been for this coast. The majority of harvested green turtles are 
juvenile females. Like mature females, at least some of the mature males are not annual 
breeders. Large juveniles and adult hawksbills, loggerheads, and leatherbacks are also 
captured, although harvest levels are much lower than for green turtles. 

Indications that green turtles are overharvested are the decrease in mean length 
and mass of harvested animals, and decrease in the mesh size of nets used. Population 
modeling studies of other long-lived, slow-maturing species indicate that increased 
mortality of juveniles and adults affect population growth the most. Results of this study 
do not indicate conclusively that marine turtle populations in Nicaragua are 
overharvested. Based on the magnitude of the green turtle fishery and its focus on large 
juveniles and adults, however, there is clearly cause for concern. 

The development of a co-managed marine turtle fishery is recommended. 
Restrictions on the number, size, and sex of animals harvested, as well as, other 
recommendations to manage the fishery are made. Recommendations for future research 
on characteristics of marine turtle populations in the region are also made. 



xi 



Resumen de la Disertacion Presentada a la Escuela de Graduados 

de la Universidad de Florida en Cumplimiento Parcial de los 

Requisitos para el Grado de Doctor en Filosofia 

PESQUERIA DE TORTUGAS MARINAS DE LA COSTA CARIBE 

DE NICARAGUA: PATRONES DE USO HUMANOS 

Y TENDENCIAS DE LA COSECHA 

Por 

Cynthia Jean Lagueux 

Mayo 1998 

Asesor Principal: Kent H. Redford, Ph. D. 
Departamento: Ecologia y Conservation de Vida Silvestre 

Se estudio la pesqueria de tortugas marinas entre los indigenas Miskitu en la costa 
caribe de Nicaragua, con fin de determinar los patrones de uso humano y las tendencias 
en la cosecha y para evaluar su impacto en las poblaciones de tortugas marinas. Los 
objetivos especificos del estudio fueron 1) caracterizar los patrones del uso humano, 2) 
cuantificar el numero de animales cosechados anualmente, 3) describir el tamano y sexo 
de los animales cosechados, 4) describir el ciclo reproductive de las tortugas verdes 
{Chelonia mydas), 5) evaluar el impacto de la pesqueria en poblaciones de tortugas 
marinas, y 6) dar recomendaciones para el manejo e investigation. 

Las tortugas verdes son el bianco de la pesqueria, mientras que las carey 
(Eretmochelys imbricata) son cosechadas en forma oportunista y los cabezones {Caretta 
caretta) y baulas {Dermochelys coriacea) son capturados incidentalmente en las redes 

xii 



puestas para las tortugas verdes. Las tortugas marinas son una fuente de proteina, 
proporcionan ingresos por venta de la carne y el caparazon, y mas recientemente son 
usadas como carnada en otras pesquerias. Los actuales niveles anuales minimos de la 
cosecha de tortugas verdes son de 10.000 a 1 1.000 animales, probablemente los niveles 
mas altos que hayan existido para esta costa. La mayoria de las tortugas verdes 
cosechadas son hembras juveniles. Igual que las hembras maduras, al menos algunos de 
los machos adultos no se reproducen anualmente. Los juveniles grandes y adultos de 
carey, cabezones y baulas tambien son capturados, aunque los niveles de cosecha son 
mucho mas bajos que los de tortugas verdes. 

Indicaciones de que las tortugas verdes son sobre cosechadas son la disminucion 
en la longitud media y el peso de los animales cosechados y la disminucion en el tamano 
del ojo de las redes usadas. Estudios que usan modelos de poblacion para otras especies 
de larga vida y maduracion lenta indican que la mortalidad de juveniles y adultos es el 
factor que mas afecta el crecimiento de la poblacion. Los resultados de este estudio no 
indican en conclusion que las poblaciones de tortugas marinas en Nicaragua son sobre 
cosechadas. Sin embargo, con base en la magnitud de la pesqueria de tortuga verde y su 
concentration en juveniles grandes y adultos, existe claro motivo de preocupacion. 

Se recomienda el desarrollo de una pesqueria co-manejada de las tortugas 
marinas. Tambien se recomiendan restricciones en el numero, tamano y sexo de los 
animales cosechados, asi como otras sugerencias para el manejo de la pesqueria. 
Igualmente se hacen recomendaciones para investigaciones futuras sobre las 
caracteristicas de las poblaciones de tortugas marinas en la region. 



Xlll 



Tanka plikanka ulbanka Kunhku kum Skul tnata alkan ra 

Marikanka kum daukan sa pura luanka ai skul ka ra tanka Florida 

Universidad kara Daktar takaia dukiara tanka pliki kaiki brabrira kaia mata 

LIH MISKANKA NICARAGUA LALMA KABUKA RA 
YUS MUNANKA TNATKA BARA ALKANKA TANKA 

Cynthia Jean Lagueux 

Bui 

Lih mairin kati 1998 

Lalka: Kent H. Redford, Daktar 

Waild nani raiaka an watla bila kan kahbaia aslika 

Miskitu nani lih yus munanka tnatkaba tanka pliki kaikan kan Nicaragua lalma 
kabuka unra, yus munanka tnanka bara alkanka tnatka ba wal tanka briaia dukiara, baku 
sin dia pitka kat sauhkanka brih auiaba lih aslika ra. Dia mihta nitkan naha tanka pliki 
kaikaia: 1) yus munan tnaka ba tanka briaia, 2) nahki pitka mani bani alkiba, 3) witin ai 
pawanka pitka alki ba tilara waihka baku mairin ba tanka kaikaia, 4) lih sahwanka tanka 
ba kau briaia dukiara, 5) dia pitka kat sauhki aula miskanka tnatka ba bui, 6) kupia 
kraukanka iaia yus munanka tnatka kum brih waia ba dukiara bakusin ai tanka pliki 
kaikaia dukiara. 

Mamiskra nani brinka paliba lih {Chelonia mydas) sakuna axbil (Eretmochelys 
imbricata) sans ra alkisa, lagrit (Caretta caretta), bara lih siksa (Dermochelys coriacea) 
ba wal alkisa kuna lih tanka kahbuia ba tilara accident ra. Kabu lih ka ba aunhka ba 



xiv 



dukiara yus munisa, baku sin winka ba atki ilpka brisa, baku sin ai miskanka nani tnatka 
walara yus munisa. Lih kau wiria alkiba 1 0,000 wina 1 1 ,000 kat alkisa, naha na aima 
wala nani wal prakbia kaka nanara kau alkisa, baha pitka alkiba wina aihkika ba mairin 
tiara lupia kau alkisa, tila bara mairin aiapra kum kum alkisa, bara sin waihka nani kum 
kum ba mani bani sip alkras sa. Baku sin lagrit bara lih siksa wahma an almuk alkisa. 

Lih ba uba alki ba tanka mamrikisa, ai paunkara kaikaia sipsma ai pawrikara bara 
piu luia bani tan nakra kau sirpi daukisma bara. Tanka pliki kaiki naniba tnatka kum wal 
mamrikisa daiwan nani rayaka yari briba wihkara ai kiamka sakisa bara man wahma an 
tiara nani ikisma bara ai daknika pawanka ra sauhkisa. Naha tanka pliki kaikan na mai 
wiras sa Nicaragua lih aslika ba tankas yus munanka kum barasa. Sakuna aima banira lih 
aialkra nani kau ailal barasa baku sin lihka alkismaba wahma, tiara nani kau alkisa, baha 
mihta sarka kum barasa lih aslika pawanka ba dukiara. 

Baha mihta kupia kraukisa lih ba tankira miskaia wakanka tnatka kum wal. Baku 
sin lih alkaia ba pitka kum bara kaiasa bara ai pawanka pitka kum sin bara kaiasa baha 
pitka baman alkaia, bara sin waihka apia kaka mairin baman alkaia laka bara kaiasa. La 
tnatka wala nani sin bara kaia sa lih yus munanka ra, bara sin lih raiaka tanka an ai 
daknika pawanka tanka ba briaia wan klauna tasbaiara. 



xv 



CHAPTER 1 
INTRODUCTION 



Humans use natural resources for food, shelter, medicine, tools, pets, curios, 
barter, and as a source of income with which to procure other goods and services. 
Current and historical uses of natural resources for subsistence and trade have been well 
documented in the literature (e.g., Robinson and Redford 1991, 1994; Jorgenson 1993; 
Rose 1993, 1996; Bodmer 1994; Bodmer et al. 1994; Jenkins and Broad 1994; Bissonette 
and Drausman 1995; Jenkins 1995; Townsend 1995; Vincent 1996; Freese 1997). Use of 
sea turtles dates back to early humans with the discovery of what appear to be green turtle 
(Chelonia mydas) bones from excavations of Borneo caves (Harrisson 1962a, b, 1967), 
and tortoiseshell products from hawksbill turtles (Eretmochelys imbricata) dating back to 
the Han dynasty of China, beginning approximately 200 B.C. (Parsons 1972). The trade 
in hawksbill shell dates back to the 15th century B.C. (Parsons 1972). 

Sea/Turtles_a£a Resource 

Sea turtles and their eggs have provided humans with a dependable resource for 
thousands of years. Nesting females and their eggs are highly vulnerable to harvesting, 
particularly the eggs, because they are an easy and relatively risk-free resource to exploit. 
Sea turtle eggs, as well as nesting females, can be a long-term, predictable resource for 

1 



humans because 1) turtles nest on their natal beaches, 2) females are iteroparous, 3) most 
species nest in relatively dense numbers, 4) nesting occurs seasonally (some species nest 
year-around at some locations), and 5) several species can nest on the same beach during 
different times of the year. 

Unlike most other marine resources sea turtles can be kept alive, out of water, for 
weeks and thus provide humans with a dependable source of fresh meat for prolonged 
periods. Although nesting females and their eggs are more accessible for harvesting, 
animals can also be captured in the water, however, more skill and equipment are 
required. Some sea turtle species congregate on foraging grounds where they feed on 
sessile prey, assemble offshore of their nesting beaches, or are predictable in their 
migratory routes to and from the nesting beach. The concentration and predictability of 
animals at known in- water locations during various times of the year or during their 
lifespan makes them nearly as accessible to harvesting as nesting females and their eggs. 

Worldwide Status of Sea Turtles 

The current status of sea turtle populations worldwide is indicated by the 
threatened status of the seven extant species (IUCN 1996). Overharvest of animals and 
their eggs for human use, incidental capture, and habitat loss and degradation due to 
coastal development are some of the primary causes of worldwide population declines 
(e.g., Bjorndal 1982; National Research Council 1990; Eckert 1995; IUCN 1997; 
Lutcavage et al. 1997). Currently, the international sale of sea turtles and their products 
is illegal among the 142 (as of September 1997, Anon. 1997) signatory nations of the 



Convention on International Trade in Endangered Species of Wild Fauna and Flora 
(CITES). All seven species of sea turtles are listed under Appendix I, species threatened 
with extinction (CITES 1992). 

Historical Harvest of Sea Turtles, ExceplNicaragua 

The harvest of sea turtles for their meat, shell, oil, and calipee, and their eggs has 
occurred for thousands of years, probably since hominids encountered female turtles, 
their eggs, and hatchlings on coastal beaches. Human impact on turtle populations prior 
to large-scale commercialization is unknown, however, population declines are well- 
documented once exploitation for commercial purposes began (Ingle and Smith 1949; 
Carr 1954; Parsons 1956, 1962, 1972; Rebel 1974; Cato et al. 1978; Bjorndal 1982; Dodd 
1982; King 1982; Milliken and Tokunaga 1987; Meylan 1997a). Although the eggs of all 
seven sea turtle species are in demand, green and hawksbill turtles have received the 
greatest pressure in both numbers of animals harvested and duration of exploitation 
(Hornell 1927; Ingle and Smith 1949; Carr 1954; Parsons 1956, 1962, 1972; Freeman- 
Grenville 1962; Rebel 1974; Cato et al. 1978; Bjorndal 1982; King 1982; Milliken and 
Tokunaga 1987; Meylan 1997a). Tortoiseshell from hawksbill turtles was among the 
items in demand and sought after by early civilizations (Parsons 1972). It carried prestige 
and indicated wealth among the upper class. Cleopatra's bathtub was reportedly made 
from hawksbill shell (Parsons 1972). Throughout various periods in history and for 
shorter periods of time, the loggerhead (Caretta caretta), olive ridley (Lepidochelys 
olivacea), Kemp's ridley (Lepidochelys kempi), leatherback (Dermochelys coriacea), and 



flatback (Natator depressus) turtles have been in demand for their skin, oil, and meat 
(Bjorndal 1982; Ross 1982). In addition to direct take, in-direct human-induced 
mortalities also occur (National Research Council 1990; Lutcavage et al. 1997). 

It is necessary to have, at least, a general awareness of the extent of historical and 
contemporary levels of direct and in-direct take on sea turtle populations to avoid the 
shifting baseline syndrome. This syndrome occurs when scientists view the baseline of 
stock size or species composition from the start of their careers and not from a historical 
perspective (Pauly 1995; Sheppard 1995). In addition, knowledge of the historical 
decline of sea turtle populations worldwide provides a perspective with which to view 
current population levels. Thus, the following section is a compilation of historical sea 
turtle exploitation worldwide, except for Nicaragua and resulting population declines by 
species and geographic region. The exploitation of sea turtles from Nicaragua will be 
presented later. 

Mediterranean andUEast Atlantic Regions 

Due to overexploitation, marine turtle populations off the coast of Israel and 
Turkey have declined dramatically since the end of World War I (WWI) (Sella 1982). At 
the peak of the season in the mid- 1930s, an estimated 30,000 green and loggerhead turtles 
were captured offshore of northern Israel (Sella 1982). Hornell (1934 cited in Sella 1982) 
reported the export of 2,000 turtles a year from Palestine to Egypt. Between 1952 and 
1965, up to 15,000 green and loggerhead turtles were harvested off the Turkish coast, 
processed and the product sent to Europe (Sella 1982). Due to a decline in harvest rates 



5 
by the mid-1960s the center of the fishery moved to another location along the coast and 
by 1965 more than 10,000 turtles, mostly greens, were captured (Sella 1982). 

By 1 967, in Madeira, an estimated 1 ,000 loggerheads were killed annually, 
primarily for human consumption and as wall hangings for the tourist trade (Brongersma 
1982). By 1979, an estimated 2,000 loggerheads were killed annually and the primary 
market had shifted to the tourist industry (Brongersma 1982). 

In 1835, on Ascension Island, up to 40 or 50 green turtles were harvested from the 
nesting beaches in a single night with an annual harvest of more than 2,500 animals 
(Anonymous cited in Parsons 1962). In the 1840s and 1850s, between 600 and 800 green 
turtles were harvested annually (Colonial Office Reports cited in Parsons 1962). By the 
1920s, an average of 60 turtles a year were exported and by 1932 no mention of exports 
were reported (Colonial Office Reports cited in Parsons 1962). 

West Indian Ocean Reg ion 

Sea turtle populations in Tanzania have probably been reduced since prehistory 
(Frazier 1982a). From the late 1800s until recently, Zanzibar was a major exporter of 
tortoiseshell, however, the scutes originated from throughout the Indian Ocean and were 
exported to Europe and Asia via Zanzibar (Frazier 1982a, b). Two thousand years of 
exploitation have decreased the number of green and hawksbill turtles on the Kenya and 
Somalia coasts (Parsons 1962; Frazier 1982a). In 1951, a turtle soup cannery was opened 
in Kenya, and by 1954, an estimated 200 turtles were captured annually to supply the 
cannery (Parsons 1962). From 1954 to 1959, 1,000 to 1,500 live turtles were exported 



annually from Kenya to England (Parsons 1962). In Mauritius, sea turtles no longer nest 
due to overexploitation (Frazier 1982b; Hughes 1982). In Madagascar, only the 
hawksbill is exploited for export, however, the green, loggerhead, olive ridley, and 
leatherback turtles are exploited mainly for local consumption (Hughes 1982). 
Tortoiseshell has been an important export for Madagascar from 1613 to the early 1970s 
(Hughes 1975). From the mid- 1800s to the mid- 1900s, a minimum of 1,600 adult 
hawksbills were harvested annually (Hughes 1973, 1975). By WW I, tortoiseshell 
exports declined sharply and by the mid-1970s annual exports were around 250 kg 
(approximately 100 animals) (Hughes 1975). Based on a survey of the southwest coast of 
Madagascar, Hughes (1971) calculated that over 13,000 turtles were harvested annually, 
50% of the harvest comprised green turtles and the remainder of the catch distributed 
approximately equally among loggerheads, hawksbills, and olive ridleys. 

The harvest of green and hawksbill turtles from the Republic of Seychelles has 
occurred since its discovery by Europeans in 1609 ( Parsons 1972; Frazier 1982a; 
Mortimer 1984; Stoddart 1984) and the decline of green turtles probably began in the late 
1700s (Mortimer 1984) and hawksbills by the 1860s (Hornell 1927). In 1780, 454 to 907 
kg of hawksbill shell were harvested, and from 1893 to 1925, 42,727 kg of tortoiseshell 
(» 30,500 animals) were exported (Hornell 1927). From 1893 to 1968, Stoddart (1984) 
reports the export of 60,780 kg of tortoiseshell (* 45,000 animals). 

Green turtles in the Seychelles have been in demand for their meat, calipee, oil, 
eggs, blood (drunk as a health tonic), shell, cawan (primarily plastron but also carapace 
scutes), and bones (Hornell 1927; Frazier 1975; Mortimer 1984). As early as 1860, 



concern was expressed over the enormous numbers of green turtles killed for their cawan 
(Hornell 1927). The most drastic decline in green turtles began in the early 20th century 
(Hornell 1927; Mortimer 1984). From 1907 to 1909, Hornell (1927) reported 
approximately 20,500 green turtles were harvested. Between 1923 and 1925, 
approximately 14,000 green turtles were harvested for only their calipee (cartilaginous 
tissue located between the belly plates) and the remains of the animals were left on the 
beach to rot (Hornell 1927; Parsons 1972). Indications that the population in the 
Seychelles was in decline was the decrease in nesting females, decrease in the number of 
animals harvested, and a decline in the heaviest animals (Hornell 1927). 

Asian Region 

Between 4,000 and 5,000 sea turtles were captured annually in the southern Indian 
state of Tamil Nadu, the time period was not given (Kar and Bhaskar 1982). Of 5,000 
olive ridley egg clutches laid along a 50 km stretch of beach in Tamil Nadu, 
approximately 90% were harvested by humans or predated by Canis spp. (Whitaker 1977 
cited in Kar and Bhaskar 1982). Prior to 1975, the state government of Orissa sold 
permits to collect approximately 2 million olive ridley eggs/yr (~ 100 eggs/clutch), which 
were sold locally, regionally, and in Calcutta (Bustard 1980; Kar and Bhaskar 1982). 
During a three month period, in 1978/1979, West Bengali fishers harvested over 21,000 
olive ridleys in front of the Orissa nesting beach (Biswas pers. com. to Kar and Bhaskar 
1982). During the 1981/1982 nesting season, an estimated 90,000 olive ridleys were 
harvested, and during the 1982/1983 season, an estimated 10,000 ridleys were landed in 






8 
West Bengal and transported inland for sale (Silas et al. 1983). Due to overharvest for 
tortoiseshell, hawksbills have been extirpated from the south coast of Sri Lanka (Frazier 
1982b). 

At one time, five species of sea turtles were found in Thailand, and all were 
exploited for their eggs. From the period 1963 - 1966 to the period 1972 - 1973, a 70% 
decrease occurred in the number of eggs collected annually at one site (Polunin 1975; 
Settle 1995). Today, green, hawksbill, olive ridley, and leatherback populations are 
seriously reduced and the loggerhead is believed to be extirpated (Polunin 1975; 
Mortimer 1988; Settle 1995). 

The Rantau Abang leatherback rookery in the State of Terengganu, Malaysia, is 
well known for its once large numbers of nesting leatherback turtles. Today, they are 
critically endangered. In the late 1950s, an estimated 2,000 females laid approximately 
10,000 egg clutches annually (Mortimer 1990). Since the 1950s, the nesting population 
has declined steadily and catastrophically. A 1978 survey reported egg yields from 
leatherbacks had declined 34% since 1956 (Siow and Moll 1982). In 1989, fewer than 
200 egg clutches were laid, a 98% decrease in nesting activity (Mortimer 1990; Chan and 
Liew 1995). In recent years, no more than 20 females nested annually (Mortimer pers. 
com.). During the 1989 nesting season, Mortimer (1990) reports that as many as 1,000 
tourists viewed a single nesting female. This catastrophic decline in nesting females is 
attributed to a combination of factors, perhaps the most important being the nearly 100% 
harvest of leatherback eggs laid during most of the present century but also adult 
mortality caused by entanglement in fishing gear. 



9 
In addition to the leatherback rookery in the State of Terengganu, there is also 

green, hawksbill, and on occasion olive ridley nesting (Siow and Moll 1982; Mortimer 
1991). Between 1956 and 1978, green turtle egg production at Terengganu has declined 
between 43% and 57%, (Siow and Moll 1982; Limpus 1994, 1997). The largest 
concentration of green and hawksbill nesting in Terengganu occurs on Pulau Redang 
Island (Mortimer 1991). Prior to 1984, nearly 100% of the green and hawksbill eggs laid 
were collected for human consumption (Mortimer 1990). Since the late 1950s, declines 
in the number of green, olive ridley, and hawksbill eggs laid in Terengganu ranged 
between 52% and 85% (Mortimer 1990). 

In 1839, on Talang Talang Kechil Island, Sarawak (one of three Sarawak islands 
known for green turtle nesting) five to six thousand green turtle eggs were collected every 
morning, the duration of this harvest rate was not reported (Hendrickson 1958; Keppel 
1847 cited in Harrisson 1962a). By the mid- 19th century, sections of beach were leased 
by the government and nearly 100% of the green turtle eggs laid were collected 
(Harrisson 1951, 1962b; Hendrickson 1958). Since 1927, there has been a > 90% decline 
in egg production on Sarawak's turtle islands (Harrisson 1962b; Limpus 1994, 1997). 

On Sabah, from 1947 to 1978, there has been more than a 50% decline, from 
706,960 eggs (» 6,670 clutches) in 1947 to 322,102 eggs (« 3,039 clutches) in 1978, in 
the number of green turtle eggs laid (Harrisson 1964, 1966, 1967; de Silva 1982; Limpus 
1994). From 195 1 to 1985, the green turtle nesting population of the Sulu Sea Turtle 
Islands of Sabah, Malaysia/Philippines has declined > 75% and possibly as much as 90% 
(Limpus 1997). 



10 
In Indonesia, between 1975 and 1978, an average 7,531 ± 1,275 turtles/yr (species 
not reported) were exported to Japan, Singapore, and the United States (Polunin and 
Sumertha Nuitja 1982; Suwelo et al. 1982). An estimated 10,000 juvenile hawksbills 
were captured annually from Sulawesi, and from 15,000 to 20,000 juvenile hawksbills 
were captured annually from Sumatra, duration of the harvest was not given (Kajihara 
1974 cited in Polunin and Sumertha Nuitja 1982). From the Java, Flores, and Banda seas, 
approximately 5,000 adult hawksbills were captured annually prior to 1971 and 30,000 
adults were captured annually after 1972 (Kajihara 1974 cited in Polunin and Sumertha 
Nuitja 1982). During 1988 and 1989, over 1.5 tones of bekko (Japanese term for 
hawksbill shell) were exported in violation of CITES to Hong Kong, Taiwan, and 
Singapore (Barr 1992). From 1934 to 1984, green turtle egg production declined more 
than 80% (Limpus 1994). Barr (1992) estimated 7 to 9 million sea turtle eggs are 
harvested annually in Indonesia, essentially 100% of the eggs laid. 

One of the largest landings of green turtles in the world occurs in Bali (Barr 1992; 
Limpus 1994, 1997). By 1950, local sea turtle populations around Bali were seriously 
depleted (Sumertha Nuitja 1974 cited in Polunin and Nuitja 1982). From 1968 to 1970, 
Sumertha Nuitja (1974 cited in Polunin and Nuitja 1982) reported the consumption of 
28,800 turtles in two districts of Bali. In 1973, a Balinese company exported 5,000 to 
6,000 stuffed sea turtles and leather from an additional 3,000 turtles each month (Polunin 
1975). More than 30,000 turtles harvested annually from throughout the Indonesian 
archipelago were landed in Bali at the height of the trade, no date was provided (Barr 
1992; Limpus 1997). In the late 1980s, the World Wildlife Fund estimated the total 



11 

harvest of green turtles in Indonesia at 50,000 (Limpus 1997). In 1990, Greenpeace 
investigators reported at least 21,000 sea turtles landed in southern Bali, although the 
Indonesian government claimed harvest levels had decreased to approximately 10,000 to 
15,000 animals annually (Barr 1992). Currently, 25,000 sea turtles, mostly large green 
turtles, are imported annually into Bali from throughout Indonesia (Limpus 1997). In 
1994, several thousand hawksbills, harvested from throughout Indonesia, were landed in 
Bali (Limpus 1997). 

Since 1956 in Irian Jaya, there has been a > 90% decline in nesting leatherback 
turtles (Limpus 1994). Approximately 60% of the leatherback eggs laid on the world's 
third largest leatherback nesting beach (north coast) were collected for local consumption 
and sale (Starbird and Suarez 1994). In addition, approximately 200 leatherbacks are 
currently harpooned off the southwest coast by local villagers for consumption (Suarez 
and Starbird 1995). The annual harvest of green turtles in Papua New Guinea is 
estimated between 10,000 and 20,000 animals (Limpus 1997). Apparently due to 
overharvesting sea turtles are no longer found feeding offshore or nesting on beaches in 
the vicinity of villages in Papua New Guinea (Spring 1982). 

In 1953, over 1 million eggs were harvested from the Philippine Turtle Islands 
(Parsons 1962). Kajihara (1974 cited in Polunin 1975) reported 5,000 adult hawksbill 
and 50,000 large green turtles were captured annually in the Sulu Sea, and between 1961 
and 1972, tortoiseshell from approximately 45,000 hawksbill were exported to Japan. 
From 1951 to 1984, there has been a > 75% decline in green turtle egg production from 
the Philippine Turtle Islands (Limpus 1994). 



12 
In Japan, between 1 880 and 1 890, 1 ,000 to 1 ,800 green turtles were harvested 
yearly from Ogasawara Island and by the mid- 1920s harvest rates had declined to fewer 
than 250 animals. Since 1973, when the Japanese regained possession of the island, 
harvest rates have been between 45 and 225 green turtles/yr (Horikoshi et al. 1994). In 
addition, Japan has been the largest importer of sea turtle products in the world with 
imports during the last 20 years representing over two million animals (Barr 1992). 

Australian Region 

In the 1920s at least two turtle processing factories operated on Northwest Islet 
and one on Heron Island, Australia (Parsons 1962). During the 1924/1925 season, 
approximately 1,600 green turtles were processed (Parsons 1962). During the 1928/1929 
season so few nesting females were available on Heron Island that nesting animals on 
nearby islands were harvested (Moorhouse 1933). For 40 years, prior to 1954, green 
turtles were harvested on the Capricorn Reef, transported to Brisbane and shipped to 
England (McNeill 1955 cited in Parsons 1962). On the west coast of Australia, 
approximately 50 animals/wk were processed in a local turtle processing plant until 1951 
(Caldwell 1 95 1 cited in Parsons 1 962). Although sea turtles are now protected in 
Australia, indigenous people in Queensland and Western Australia are allowed to take 
turtles for their own use (Limpus 1982). It is estimated that 10,000 green turtles are 
harvested annually from the Torres Strait, of these approximately 4,000 are harvested by 
Torres Strait Islanders and used locally, and the remainder are harvested by Papua New 



13 
Guineans and sold in their coastal markets (Daly 1990; Limpus 1982). Nearly 100% of 

the eggs laid near indigenous communities are harvested (Limpus 1982). 

Central Pacific Ocean Region 

Coastal inhabitants throughout the Central Pacific Ocean have harvested marine 
turtles for thousands of years. Marine turtle populations throughout the islands have 
declined within historical times (Balazs 1982). In the Caroline Islands, the harvest of 
marine turtle eggs is uncontrolled and occurs on all the islands in the group (McCoy 
1982). Between 1985 and 1989, scutes from approximately 22,300 hawksbills were 
exported to Japan from the Solomon Islands and Fiji (Daly 1990). Prior to mid- 1994, an 
estimated 2,000 hawksbills/yr were harvested from foraging grounds in Fiji (Limpus 
1997). 

Eas tern Pacific Oce an Region 

Mexico began the commercial exploitation of olive ridleys in 1961 (Marquez et 
al. 1976; Cato et al. 1978). Both Mexico and Ecuador exported large quantities of olive 
ridley and Pacific green turtle skins and leather to Japan, France, Spain, Italy and the 
United States (Pritchard 1978; Mack et al. 1982; Milliken and Tokunaga 1987). From 
1948 to 1956, approximately 60 tones of olive ridleys/yr were harvested and in the early 
1960s, between 250 and 500 tones/yr were harvested. During the peak period of 
exploitation, between 1965 and 1969, over 30,000 tones/yr of olive ridleys were 
harvested (Marquez et al. 1976), representing approximately 700,000 animals (Marquez 
unpubl. data cited in Cliffton et al. 1982). However, according to Carr (1972), the 



14 
Mexican government underestimated the total catch, he estimated more than a million 
olive ridleys were harvested in 1968 alone. The harvest of olive ridleys had been so 
intensive that at Piedra de Tlacoyunque, one of only four Pacific coast Mexican arribada 
(Spanish for mass arrival of females on a nesting beach) nesting beaches, the aggregation 
of turtles had been reduced from 30,000 to only a few hundred between 1968 and 1969 
(Carr 1972; Pritchard 1979). By the early 1970s, three of the four Mexican olive ridley 
arribada populations had been destroyed and the remaining location of mass nesting, 
Playa Escobilla, Oaxaca, was being severely exploited (Carr 1967, 1979; Frazier 1981). 

In 1977 and 1978, an estimated 70,000 and 58,000 olive ridleys were harvested 
from Playa Escobilla, respectively (Cliffton et al. 1982). The decrease in size and 
number of arribadas that occurred at Playa Escobilla indicated that the nesting 
population was overharvested (Cliffton et al. 1982), however, the harvest continued. 
From 1980 to 1985, the average annual harvest of olive ridleys was 32,343 (Hernandez 
M. and Elizalde A. 1989 cited in Rose 1993). Harvest quotas were reduced from 48,944 
in 1980 to 23,000/yr between 1986 to 1990 (Penaflores S. and Nataren E. cited in Rose 
1993). In 1989, 2 to 12 boats illegally harvested 80 to 600 turtles/day in front of Playa 
Escobilla (Blanco-Casillo 1990). In May 1990, Mexico declared a permanent ban on all 
harvest and trade in sea turtles and their products (Aridjis 1990; Rose 1993). 

At the turn of the century, an estimated 1,000 green turtles/mo were harvested 
from Baja California and sent to San Diego, California (O'Donnell 1974). Green turtles 
once nested along the coasts of Nayarit, Sinaloa; southern Sonora; and Baja California, 
Mexico; however, today only the olive ridley nests in these areas (Felger and Cliffton 






15 
1977). The increase in human population and subsequent exploitation of nesting green 
turtles are blamed for the disappearance of these northern Pacific Mexico nesting 
populations (Felger and Cliffton 1977). As larger turtles became more scarce in the late 
1960s, juvenile greens were harvested at a rate of approximately 250 to 360 turtles/day 
(Cliffton et al. 1982). In the Gulf of California, for a three to four month period in the 
winter of 1975, five turtle boats harvested an estimated 140 to 175 green turtles/wk as the 
turtles lay dormant in the mud (Cliffton et al. 1982). The number of turtles had declined 
so drastically by 1975, Cliffton et al. (1982) reported that it took five boats of fishermen 
with diving gear to capture as many turtles as one boat of Seri Indians with harpoons in 
the 1960s. By 1977, Mexican fishermen had destroyed the population of dormant green 
turtles in the Gulf of California (Felger and Cliffton 1977). 

Green turtles also once nested along the southern Pacific coast of Mexico; 
however, today only one major nesting site remains, Colola-Maruata Bay, Michoacan 
(Cliffton et al. 1982). Nahuatl Indian informants reported there were 10 to 20 times more 
nesting green turtles in 1970 than in 1979 (Cliffton et al. 1982). Over 4,500 metric tons 
of green turtles were landed on the Pacific coast of Mexico (Marquez et al. 1976), 
estimated to represent approximately 125,000 adult and subadults (Cliffton et al. 1982). 
In the early 1970s, the Nahuatl Indians estimated they harvested 15,000 to 20,000 
eggs/night at Maruata Bay and 70,000 eggs/night at Colola (Cliffton et al. 1982). In 
1978, at least 10,500 green turtles were legally harvested from Michoacan and Jalisco (A. 
Suarez pers. com. to Cliffton et al. 1982). In 1979, although a closed season had been 



16 
established, approximately 3,000 green turtles were illegally harvested (Cliffton et al. 
1982). 

In 1685, near Coiba Island, Panama, Dampier reported harpooning sea turtles 
every day (Parsons 1962). Reports of abundant numbers of turtles continued in 1741 and 
1794. By 1956, however, only a few turtles were reported (Parsons 1962). During the 
1970s, marine turtle populations declined drastically (Cornelius 1982). From 1964 to 
1976, over 96,000 kg of hawksbill shell, representing approximately 55,670 animals, 
were officially exported from Panama (Vallester 1978 cited in Cornelius 1982). 

In Ecuador, during the 1 970s, at least six companies were involved in exporting 
frozen sea turtle meat for human consumption and salted skin for the leather trade (Green 
and Ortiz-Crespo 1982). From 1970 to 1978, up to 90,000 olive ridleys/yr were 
processed and exported. For 1977 alone, Japan imported 66% and Italy imported 25% of 
the skins exported from Ecuador (Green and Ortiz-Crespo 1982). The majority (72%) of 
the meat was imported by the United States (Green and Ortiz-Crespo 1982). 

In Peru, from 1965 to 1985, the mean annual turtle harvest was estimated at 1,222 
± 1,636, and in 1987, it was estimated at > 22,200 animals (Aranda and Chandler 1989). 
The harvest most likely represented a combination of greens, olive ridleys, and 
leatherbacks, although the species harvested was not provided. The decrease in mesh size 
of the nets used in the fishery from a 59 cm bar in 1979 (Hays Brown and Brown 1982) 
to a 25 cm bar in the early 1990s (Vargas et al. 1994) could indicate a decrease in the 
mean size of animals due to overharvest. 



17 
Eastern United States Region 

At least four species of sea turtles were harvested along the east, Gulf of Mexico, 
and west coasts of the United States. From 1880 to 1947, a minimum 1.5 million kg of 
sea turtles or ~ 10,700 animals (estimated number of animals based on x = 136.2 
kg/green turtle (National Research Council 1 990)), principally greens, were landed in 
Florida (Ingle and Smith 1949; Rebel 1974). From 1950 to 1971, a minimum 509,500 kg 
of green turtles or ~ 3,740 greens (estimated number of animals based on the same x = 
136.2 kg/green turtle), and from 1951 to 1971, a minimum 66,535 kg of loggerheads and 
Kemp's ridleys combined or from ~ 590 - 1,665 animals (estimated number of animals 
based on x = 1 13 kg/loggerhead or x = 40 kg/Kemp's ridley (National Research Council 
1990)), were landed in Florida (Rebel 1974). From 1890 to 1976, a minimum 4.3 million 
kg of sea turtles (ranging from ~ 31,600 to 38,100 animals based on mean mass of green 
or loggerhead turtles as described above) were landed at eight U.S. states and territories 
(Witzell 1994). An estimated 1 1,000 turtles (loggerheads, Kemp's ridleys, and greens) 
were unintentionally killed annually on the United States east coast and Gulf of Mexico 
by shrimp trawlers (Henwood and Stuntz 1987). In the United States, indirect human- 
induced mortality of loggerheads was estimated at 5,550 to 55,500 animals annually and 
for Kemp's ridleys it was estimated at 555 to 5,550 animals annually. This mortality was 
caused by shrimp trawls, discarded fishing gear and debris, other fisheries, dredging, 
collisions with boats, oil-rig removal, and electric power plants (National Research 
Council 1990). 



18 

Gulf of Mexico Reg ion 

Up to the mid-1950s, as many as 2,000 nesting green turtles/yr were harvested 
from the Yucatan Peninsula, Mexico and exported to the United States (Parsons 1962). 
Between 1949 and 1969, > 3.6 million kg (x = 173,000 kg/yr) of green turtles and > 
800,000 kg (x = 47,800 kg/yr) of loggerheads were harvested annually (Rebel 1974). 
Annually, 200 kg of hawksbill shell was harvested from the Yucatan, no time period is 
provided (Carranza 1967 cited in Rebel 1974). During the mid-1970s, the established 
quotas for the east coast of Mexico ranged from 420 turtles to 2,000 turtles/yr, divided 
evenly between greens and loggerheads (Cato et al. 1978). Populations of four of the five 
species (hawksbill, loggerhead, green, and Kemp's ridley) of sea turtles that occur on the 
east coast of Mexico have declined (Hildebrand 1982). The Kemp's ridley is the most 
endangered of the seven species of sea turtles (Ross et al. 1989; Pritchard 1997). Decline 
in the nesting population began prior to 1966 with high levels of egg exploitation 
(Pritchard and Marquez 1973, Ross et al. 1989, Marquez 1994), and continues today due 
to incidental capture by shrimp trawlers (Ross et al. 1989; National Research Council 
1990; USFWS/NMFS 1992). 

Greater Caribbean Reg ion 

In the greater Caribbean, sea turtles played an important role in the expansion and 
dispersal of Europeans to the New World during the period of discovery, conquest, and 
colonization (Carr 1954; Parsons 1962). Carr (1954) credited the green turtle as being the 
single most important dietary factor that supported the opening up of the Caribbean to 



19 
European colonization. The green turtle provided ship crews with a source of fresh meat 

and allowed for extended periods of travel (Carr 1954; Great Britain Colonial Office 
Reports 1929 cited in Parsons 1962). Because of overexploitation, however, many 
nesting and foraging populations throughout the greater Caribbean were depleted or 
extirpated during early European expansion (Carr 1954; Parsons 1962, 1972; Dodd 1982; 
King 1982). 

Parsons (1962) suggests that commercial turtling in the west Atlantic probably 
began in Bermuda, where at one time, there was a large assembly of nesting and foraging 
green turtles (Ingle and Smith 1949; Parsons 1962). However, in spite of legislation 
established in 1620 to protect sea turtles, within 150 years of English settlement sea turtle 
populations around Bermuda were so reduced that a commercial harvest was no longer 
profitable (Garman 1884b cited in Carr 1952; Parsons 1962). Carr (1954) suggests that 
Bermuda was probably the first documented green turtle rookery to be extirpated. In 
1671, Bahamian officials were asked to prepare legislation that would protect green 
turtles against overexploitation, however, no action was taken (Great Britain Public 
Record Office 1889 cited in Parsons 1 962). By the 1 700s, the Bahamian green turtle 
population was also destroyed (Carr 1954; Dr. Archie Carr (interview) 1984). 

The Cayman Islands were once known for the size of their green turtle rookery, 
which supported the largest turtle fishery in the New World (Lewis 1940; Carr 1954; 
Parsons 1962; King 1982). As early as 1503, Columbus recorded the massing of turtles 
around the Cayman Islands (Carr 1954; Morison 1942 cited in Parsons 1962) and Long 
(1774 cited in Lewis 1940) described how during the nesting season there were so many 



20 
turtles migrating towards the Cayman Islands that lost ships would navigate by the sound 

of their swimming towards the Caymans. For almost 200 years, sailing ships from many 
nations (e.g., British, Dutch, and French) arrived each summer to "turn turtle" (while on 
the nesting beach female turtles are turned over on their backs to prohibit them from 
returning to the water) (Parsons 1962). In 1684, it was reported that approximately 2,000 
inhabitants of Port Royal, Jamaica, as well as, an unknown number of inland inhabitants, 
fed daily on green turtle meat (Molesworth cited in Parsons 1962). By 1802, a little less 
than 1 50 years after English settlement had begun, green turtle populations had become 
so depleted that Cayman turtlers sailed first to the south coast of Cuba, then the Gulf of 
Honduras, and finally to the Miskito coast of Nicaragua in search of ever dwindling 
stocks of turtles (Lewis 1940; Carr 1954; Parsons 1962; King 1982). 

HistojicaLHan^lMSe^/rurtles from Caribbean Waters of Nicaragua 

Green Turtles 

Turtles have been harvested from Nicaragua's coastal waters and beaches for at 
least the past 400 years (Carr 1954; Parsons 1962; Roberts 1965; Dampier 1968; 
Nietschmann 1973; Mortimer 1981; Montenegro Jimenez 1992; Lagueux 1993). 
Unfortunately, no information is available on harvest rates prior to European arrival. 
However, as early as 1633, the English had established a trading station at Cabo Gracias a 
Dios (near the Honduras/Nicaragua border) (Parsons 1962). Parsons (1962) speculated 
that the Miskitu Indians taught the English and their colonists how to turtle. By 1 722, 
Jamaican and possibly Cayman boats were annually visiting the Miskito Cays of 



21 
Nicaragua to catch and purchase green turtles and hawksbill shell from the Miskitu 
Indians (Fernandez cited in Parsons 1962). However, turtling by the Cayman Islanders 
off the coast of Nicaragua did not occur with any regularity until the early 1800s (Lewis 
1940; Parsons 1962). Simmonds (cited in Parsons 1962) reported that by 1878, up to 
15,000 turtles, although the species landed was not stated the majority were probably 
green turtles, annually were landed in Europe, most of them having been caught by the 
Cayman fleet which was known to harvest turtles in Nicaraguan waters. 

During the first-half of the 20th century approximately 2,000 to 4,000 green 
turtles were harvested annually from the Nicaragua coast by Cayman turtlers (Ingle and 
Smith 1949; Parsons 1962). By the mid-1960s, after several hundred years of 
exploitation, the Nicaraguan government no longer permitted Cayman Islanders to turtle 
within their waters (Nietschmann 1973, 1976). Apparently, the Nicaraguan government 
was not motivated by its concern for turtle conservation, but by its interest in securing a 
constant supply of turtles for their newly established turtle processing plants (Rainey and 
Pritchard 1972) and to decrease competition with other countries on the international 
market. In late 1968, the first of three Nicaragua marine turtle packing plants began 
processing green turtles for export (Nietschmann 1973, 1974). From 1966 to 1976, 
Nicaragua exported 445,500 kg (equivalent to approximately 10,000 animals) of sea 
turtle products into the United States alone during 7 of these 10 years (Cato et al. 1978). 
From 1969 to 1976, up to 10,000 green turtles were harvested annually from the offshore 
waters of Nicaragua for local and foreign consumption (Nietschmann 1972, 1973). By 
1977, the processing plants were closed and Nicaragua became a signatory of CITES 



22 
(Hemley 1994). From 1985 to 1990, the sale of 16,700 green turtles was recorded in the 

Puerto Cabezas, Nicaragua market (Montenegro Jimenez 1992). 

Hawksbill Turtles 

Hawksbills have been harvested from the offshore waters of Caribbean Nicaragua 
and from the nesting beaches of the mainland and offshore cays for probably as long as 
green turtles have been harvested from this region. Annual boat trips by the Miskitu 
Indians to southern Nicaragua, Costa Rica, and to northern Panama to harvest hawksbills 
is reported for as early as the 1600s (Parsons 1972; Nietschmann 1973). In the mid- 18th 
century, annual exports of tortoiseshell to Europe averaged 6,000 to 10,000 lbs (2,722 - 
4,536 kgs) (Parsons 1956, 1972). The shell was traded by the Miskitus to the English for 
cloth, guns, rum, and other goods (Parsons 1956, 1972; Nietschmann 1973). During a 
12-mo period beginning in October 1968, 41 hawksbills were harvested by one Miskitu 
Indian village (Nietschmann 1972, 1973). For the first six months of 1969 compared to 
the same time period in 1971 the harvest of hawksbills by one village increased almost 
400%, from 27 to 107 animals (Nietschmann 1972, 1973). During the early 1970s, 
approximately 1,000 to 1,200 hawksbills were harvested annually and exported to Japan 
(Nietschmann 1981). Based on Japanese customs statistics, from 1970 to 1986, 
Nicaragua exported 14,519 kg of tortoiseshell to Japan, representing approximately 
13,000 hawksbills (Milliken and Tokunaga 1987). Although Nicaragua has been a 
signatory of CITES since 1977 (Hemley 1994), approximately 20% of this trade occurred 
post- 1977 (Milliken and Tokunaga 1987). 



23 
Loggerhead anaU^eatherhackJjurtles 

Very little is known about the loggerhead in Nicaraguan waters. Unconfirmed 

reports indicate that loggerheads nest infrequently on Nicaragua's Caribbean coast (Carr 

et al. 1982). Animals are captured incidentally in nets set for green turtles. Although 

loggerhead meat is not eaten, throat and shoulder skin from loggerheads, as well as, green 

and hawksbill turtles was exported to Europe (Nietschmann 1972, 1981; Bacon 1975). 

Leatherback turtles are found in Nicaraguan waters and possibly nest in low numbers on 

the mainland (Bacon 1975; Carr et al. 1982; this study). Prior to this study, nothing was 

known about their capture from Nicaragua's Caribbean waters. 

Marine Turtles and the Nicaragua Fishery 

Today, the largest remaining foraging population of green turtles in the Atlantic 
Ocean is located in coastal waters of eastern Nicaragua (Carr et al. 1978). The extended 
continental shelf found in this region comprises cays, coral reefs, and extensive seagrass 
beds. Green turtles use this area for foraging, developmental habitat, and as a migratory 
pathway to the Tortuguero, Costa Rica nesting beach. Data from international tag 
recoveries demonstrate that green turtles tagged in the Bahamas, Bermuda, Costa Rica, 
Cuba, Florida, Grand Cayman, Mexico, Panama, and Venezuela have been captured in 
Nicaragua's offshore waters (Sole 1994; Bjorndal and Bolten 1996; Bagley in litt.; 
Bresette in litt.; Ehrhart pers. com.; Lagueux pers. obs.; Meylan in litt.; Moncada pers. 
com.). 



24 
Marine turtles and their products no longer are legally exported from Nicaragua, 

however, Miskitu and Rama Indians continue to conduct a legal marine turtle fishery for 
local consumption centered on the green turtle. In 1965, the Nicaragua government 
established a closed season to protect sea turtles in their Caribbean waters for several 
months/yr, although turtles occur year around (Nietschmann 1972, 1973; Rebel 1974; 
Weiss 1976; Bacon 1981; Peralta Williams 1991; Montenegro Jimenez 1992; pers. obs.). 
Because the law is not enforced, and some have argued, unenforceable (Nietschmann 
1973; Peralta Williams 1991; D. Castro pers. com.), turtles continue to be harvested 
during the closed season. 

Hawksbill turtles are opportunistically captured by lobster divers, in nets set for 
green turtles, and while nesting on mainland beaches or offshore cays. Juvenile and adult 
hawksbills tagged in at least three countries (Costa Rica, Mexico, and the U.S. Virgin 
Islands) throughout the greater Caribbean have been harvested in Nicaraguan waters 
(Carr et al. 1966; Carr and Stancyk 1975; Bjorndal et al. 1985; Hillis 1994; Garduno in 
lift.; see Meylan 1997b for review). Green and hawksbill turtle meat are used for 
subsistence and green turtle meat is sold in local markets. Hawksbill shell is sold to local 
artisans who fashion various jewelry items that can be found for sale throughout the 
country. 

Loggerhead and leatherback turtles are not targeted in the fishery, however, they 
are also captured in nets set for green turtles. Two loggerheads, one tagged in Panama 
(Meylan in lift.) and one in the Azores, Portugal (Bjorndal in lift.) were recovered in 
Nicaragua. Recently, there is a demand for loggerhead and green turtle meat as bait in 



25 
lobster traps and the hook and line fishery for shark. Almost nothing is known about 

populations of loggerheads and leatherbacks in Caribbean waters of Nicaragua or their 
use of this habitat. 

The status of green, hawksbill, and possibly loggerhead populations in the greater 
Caribbean, will depend, in part, on fishing activities of the Miskitu Indians. Offshore 
waters of Caribbean Nicaragua are home to a large number of sea turtles representing 
several species and nesting populations, as well as, the influx of animals from other areas 
of developmental habitat throughout the greater Caribbean. Thus, the legal, unregulated 
marine turtle fishery of Caribbean Nicaragua has the real possibility of severely 
impacting marine turtle populations throughout the greater Caribbean and needs to be 
assessed. 

To date, no attempt has been made to evaluate the impact of the Nicaragua marine 
turtle fishery on turtle populations, although marine turtles have been harvested from 
these waters for at least 400 years and the area supports the largest remaining green turtle 
foraging population in the western Atlantic Ocean. Prior to the current study, only 
cursory information about the fishery was available and nothing was known about its 
current status. For these reasons, I focused my research on quantifying and describing 1) 
human patterns and use of the marine turtle harvest and 2) biological parameters of the 
animals harvested. From these data, I have conducted a preliminary evaluation of the 
impact of this fishery on marine turtle populations in the region using absolute and 
relative capture efforts and biological parameters of the harvested animals over time. The 
evaluation of the fishery is based on data collected over a relatively short period of time 



26 

(in relation to generational time of the resource), however, these results provide base-line 
information with which to compare subsequent years of harvest data. An evaluation of 
the impact of the fishery is necessary to provide the basis for developing management 
strategies to regulate the fishery. 

This dissertation is organized into six chapters, including the current chapter. In 
Chapter 2, 1 describe and characterize the human patterns and use of the marine turtle 
harvest, including a description of fishery participants, harvest locations, harvest methods 
and their efficiency, and the human distribution of harvested animals. In Chapter 3, 1 
quantify the number of harvested animals by species, size, and sex for the majority of the 
Caribbean coast of Nicaragua and analyze harvest rate and changes in size over time. In 
Chapter 4, 1 describe the reproductive cycle and status of a subset of harvested green 
turtles. In Chapter 5, 1 conduct a preliminary evaluation on the impact of the fishery 
based on historical information from the region, indices of current capture effort and 
demographics of harvested animals over time, and results from the literature on 
population modeling of long-lived organisms. In the final chapter, Chapter 6, 1 make 
recommendations for the development of a co-managed marine turtle fishery and provide 
management recommendations for the fishery based only on biological constraints of the 
species. Management options for the marine turtle fishery that can impinge on social, 
economic, and cultural aspects of the turtlers, turtle butchers, and coastal inhabitants will 
need to be discussed and agreed on among the turtlers, turtling-community 
representatives, and regional and central government officials. I also provide 
recommendations for future research. 



CHAPTER 2 
HUMAN USE PATTERNS 



Introduction 



Natural Resource U se 

Throughout the world natural resources are harvested to meet dietary, medicinal, 
cultural, religious, and financial human needs and wants (e.g., Robinson and Redford 
1991, 1994; Jorgenson 1993; Rose 1993, 1996; Bodmer 1994; Bodmeretal. 1994; 
Jenkins and Broad 1994; Bissonette and Drausman 1995; Jenkins 1995; Townsend 1995; 
Vincent 1996; Freese 1997). As a result, many plant and animal populations have been 
severely reduced or depleted. To mitigate negative impacts of human use or to aid in the 
recovery of depleted populations, it is necessary to manage human resource use. 

Effective resource management cannot occur without a knowledge of human use 
patterns, such as, how and where resources are harvested, uses of the resources, and who 
are the beneficiaries. It is also important to quantify harvest effort, yield, and distribution 
of the harvest among resource consumers. These types of data can aid in the 
development and implementation of management schemes that mitigate restrictions 
imposed on resource users, meanwhile, improving compliance with regulations and the 
probability of long-term resource availability. In addition, monitoring changes in human 
use patterns, such as, harvest effort and rates, and areas of resource extraction, can 

27 



28 
provide information about the sustainability of the harvest and the impacts of human use 

on resource populations. Thus, the identification and quantification of human use 

patterns are important for management schemes to be successful and can provide data 

critical in monitoring population trends in a resource. 

Human Use of Sea Turtles 

Historical use of sea turtles by humans has been well documented in chronicles of 
early travelers and by the scientific community because of strong interest in these animals 
(Hornell 1927; Ingle and Smith 1949; Parsons 1962; Dampier 1968; O'Donnell 1974; 
Frazier 1980; Bjorndal 1982). Marine turtles are exploited for their eggs, meat, shell, 
skin, and other products. Although much of the literature is descriptive, a few studies 
have quantified human use patterns of sea turtles, e.g., the use of olive ridley 
(Lepidochelys olivacea) eggs in Honduras (Lagueux 1989, 1991) and green {Chelonia 
mydas) and hawksbill {Eretmochelys imbricata) turtles in the Solomon Islands (Broderick 
pers. com.), Seychelles (Mortimer 1984), and Nicaragua (Nietschmann 1972, 1973, 
1979a; Weiss 1975, 1976). 

Marine turtles on the Caribbean coast of Nicaragua have been harvested by 
Amerindians since before the arrival of Europeans to the New World. These peoples, 
now known as the Miskitu Indians, have long been recognized for their turtling skills 
(Parsons 1962; Roberts 1965; Dampier 1968; Nietschmann 1972, 1973). Their turtle 
harvesting methods were described in the early 1800s by Roberts (1965), in the mid- 
1800s by Squier (1965) and Bell (1989) and in the early 1900s by Conzemius (1932). 



29 
Detailed accounts of natural resource use by two Miskitu turtling communities were 
reported by Nietschmann (1972, 1973) and Weiss (1975, 1976). 

Subsequent to the studies by Nietschmann (1972, 1973, 1979a) and Weiss (1975, 
1976) in the late 1960s and early 1970s, there have been several major events in eastern 
Nicaragua that have had a potential impact on human use patterns of marine turtles on 
this coast. Between 1969 and 1977, three marine turtle slaughter houses opened and 
closed; in 1977, Nicaragua became a signatory of the Convention of International Trade 
in Endangered Species (CITES; Hemley 1994); and most recently, in 1990, the country 
ended a 10-yr long civil war. As a result of these events, human use patterns described 
by Nietschmann (1972, 1973, 1979a) and Weiss (1975, 1976) are probably no longer 
indicative of current use patterns for the region. Their studies also lack a broader 
perspective of Miskitu Indian turtling practices because they focussed on resource use in 
a single community. 

The current Miskitu and Rama Indian marine turtle fishery is a legal, uncontrolled 
harvest of green and hawksbill turtles. Although, in 1965, the Nicaragua government 
established a closed season to protect green turtles in their Caribbean waters for several 
months/yr (Nietschmann 1972, 1973; Rebel 1974; Weiss 1976; Bacon 1981; Peralta 
Williams 1991; Montenegro Jimenez 1992; pers. obs.) the closed season has been 
ineffective. The duration of the closed season has, apparently changed from two months, 
15 May to 15 July, in the 1970s (Nietschmann 1972, 1973; Rebel 1974; Weiss 1976; 
Bacon 1981) to four months, 1 April to 31 July, in the 1980s and 1990s (Peralta Williams 
1991; Montenegro Jimenez 1992 pers. obs). Although restrictions under the law are not 



30 
clear, the closed season has at different times varied in duration and included a total ban 

against the harvest of turtles, a ban against the commercialization of marine turtles, and a 
ban against the harvest of females (Nietschmann 1972, 1973; Weiss 1976; Montenegro 
Jimenez 1992). Several sources agree, however, that the law is not enforced, and some 
have argued that it is unenforceable (Nietschmann 1973; Peralta Williams 1991; D. 
Castro pers. com.). This is evident by the number of green turtles of both sexes landed 
during the closed season months (see Chapters 2 and 3). In addition, in 1997, 
enforcement of the closed season displaced the sale of green turtles from Puerto Cabezas 
to the Rio Coco region of the country (D. Castro pers. com.), located on the border with 
Honduras. Thus, in 1997, the result of the closed season was that green turtles were 
distributed to non-traditional markets rather than reducing the harvest. 

Human use patterns need to be determined to understand current impacts on turtle 
populations, monitor changes in human use patterns, and to improve our ability to 
successfully manage natural resource use. In this chapter, I characterize the following 
aspects of the turtle fishery: who fishes for marine turtles, how and where turtles are 
captured, and uses of marine turtles. In addition, I analyze the capture rate and human 
distribution of harvested turtles on temporal and spatial scales. These data can be used as 
a basis in the development of management recommendations for the marine turtle fishery. 
These data are not only important in a current evaluation of the fishery but also for 
establishing baseline levels with which future data can be compared. Identifying changes 
in capture per unit effort also provides a means to indirectly monitor turtle population 
trends and can be used as an indicator of overharvest and population decline. 



31 



Methods 



Study Site 



Research was conducted on the Caribbean coast of Nicaragua (Figure 2.1). 
Politically, the eastern one-third of the country, including the inhabited Corn Islands and 
numerous offshore cays, is divided primarily into the Region Autonoma del Atlantico 
Norte (RAAN) and the Region Autonoma del Atlantico Sur (RAAS). Three coastal 
commercial centers are located in these regions: Puerto Cabezas in the RAAN, and 
Bluefields and Corn Island in the RAAS. Outside these commercial centers people on the 
coast reside in the following ethnically identified communities: Miskitu Indian, Miskitu 
Indian/Creole mix, Carib, and Rama Indian. Creoles are a racial and cultural mixture of 
African, European, and Amerindian traits (Hale and Gordon 1987). Caribs, or Garifunas 
as they are also known, are of African and Amerindian descent. They arrived in 
Nicaragua via Honduras as displaced slaves from the Caribbean island of St. Vincent 
(Hale and Gordon 1987). 

On the Caribbean coast of Nicaragua, turtlers are Miskitu Indians, Creoles, or 
Rama Indians. In the RAAN, turtlers are Miskitu Indians. Most are bilingual, speaking 
Miskitu and Spanish, and many of the older inhabitants are trilingual, also speaking 
English. Miskitu is the language of everyday use in the RAAN and people identify 
themselves ethnically as Miskitu. 






Figure 2. 1 . Caribbean coastline of Nicaragua with coastal communities and towns. 



33 



"- Miskito Cays 




Walpasiksa 
Prinzapolka 



Caribbean 



13° Cd "I \ *"M 

q Sandy Bay Sirpi ^ 1 

*^ Rio Grande Bar^^ 1 

Tasbapaune. 
-*• ^ 

Set Net 
Regi6n Autdnoma 

del Atlantico Sur 
(RAAS) 

— Bluefie 

Rama Cay ■ 



French Cay 




f Man O' War Cay 

"Tyra Cay 
•••Kings Cays 



Pearl Cays 



Corn Islands 



-100 Fathom Contour Line 
-Regional Boundary 



i 




100 



kms 



34 
In the RAAS, the ethnic identity of the turtling communities is Miskitu Indian, 
Miskitu Indian/Creole mix, or Rama Indian. In the Miskitu Indian/Creole mix 
communities, inhabitants are from a Miskitu ancestry but many have assimilated a 
Creole identity (Hale 1987; R. Carlos pers. com.). Creole English is spoken in the 
Miskitu Indian/Creole mix communities, particularly among the younger inhabitants. In 
one RAAS turtling community it was reported that many of the younger people no longer 
speak Miskitu (R. Carlos pers. com.). Rama Indian communities are located south of 
Bluefields. Residents from at least two of these communities harvest sea turtles. 

The continental shelf of Nicaragua extends approximately 200 km at its widest 
point eastward from Cabo Gracias a Dios (near the Honduras/Nicaragua border) to 
approximately 20 km wide at its narrowest extension near the Costa Rican border. This 
extensive shelf provides Nicaragua with a vast area of productive marine ecosystems 
including mangrove and coral cays, underwater reefs, and seagrass pastures that supports 
many commercially and locally valuable resources, such as, shrimp, lobster, scale fish, 
and four species of marine turtles. 

The marine turtle fishery occurs in Nicaragua's offshore Caribbean waters. The 
main turtling area in the RAAN is located offshore approximately 48 to 80 km. The 
Miskitu Indian/Creole mix communities located along the northern coast of the RAAS, 
turtle in areas located approximately 16 to 24 km offshore. Rama Indian turtling areas 
are located just offshore near French and Pigeon (located just north of French Cay) Cays. 
In addition, turtles can be captured just offshore in the RAAN and RAAS as they migrate 
to and from the nesting beach located at Tortuguero, Costa Rica (Figure 2.1). 



35 
Geographic_andJIemporal Distribution of Data Collection 

In the RAAN, at the time of the study, five communities were known to fish for 
green turtles. These were Awastara, Dakra, Krukira, Pahra, and Sandy Bay (Figure 2.1). 
Beginning in April 1996 green turtles harvested by the community of Walpasiksa were 
also landed at Puerto Cabezas. Data on the turtle harvest were recorded in the 
communities of Awastara, Dakra, and Sandy Bay and when turtles were landed at the 
commercial center of Puerto Cabezas. Data on the harvest of sea turtles by the 
communities of Krukira, Pahra, and Walpasiksa were recorded only when turtles were 
landed in Puerto Cabezas because there were insufficient funds and the residents of 
Krukira were unwilling to participate in the study. 

In the RAAS north of Bluefields, four communities were known to fish for green 
turtles, at the time of the study. These were Rio Grande Bar, Sandy Bay Sirpi, Set Net, 
and Tasbapaune (Figure 2.1). Along the southern coast of the RAAS, south of 
Bluefields, at least two communities of Rama Indians also fish for turtles but were not 
included in the study due to financial constraints. Data on the turtle harvest in the RAAS 
were recorded in the four communities listed above. At the time of the study, no 
additional Caribbean Nicaragua communities were known to fish for marine turtles. 

I trained local community residents to collect the data. In addition, I conducted 
informal interviews in communities and commercial centers during several short trips to 
Nicaragua in April and May 1992, November and December 1995, December 1996, and 
during a longer period of residence on the coast from November 1993 to February 1995. 
Data on who participates in the turtle fishery, types of boats used, and methods used to 



36 
capture turtles were collected opportunistically. In the indigenous communities, my key 
informants were community judges, secular and religious leaders, and turtlers; in 
commercial centers they were the turtle butchers and employees of each municipality. 

At each of the eight turtling communities and commercial center, one or two 
residents of the site were employed as data collectors. Data collectors were selected 
based on their: 1) acceptance in this role by community members, 2) interest and 
availability in conducting the work, 3) ability to conduct the work, and 4) prior 
experience in collecting and recording data. Three of the data collectors employed in this 
study had worked previously with other researchers and had experience recording various 
types of data. I trained each data collector and supervised data collection. When a turtle 
boat arrived at any of the eight sites data collectors recorded the following: 1) turtlers 
community of residence, 2) date, 3) number of days turtling, 4) capture method used, 5) if 
nets were used, how many, 6) capture location, 7) number of animals of each species 
captured, and 8) where captured turtles were consumed or sold. 

The period for which data are available from each site varies and is not always 
continuous (Table 2.1). Inconsistencies were due to the following factors: differing 
initiation dates of data collection, insufficient funds to continue employment of 
collectors, or unforseen circumstances (e.g. datasheets were stolen from the data collector 
or damaged by rain). Depending on the site, the number of months for which data were 
collected ranged from 29 mo for Awastara and Dakra to 64 mo in Sandy Bay Sirpi. The 
percentage of months for which data were collected within the data collection period 
ranged from 66.7% for Rio Grande Bar to 100% for Set Net (Table 2.1). 



37 

Table 2. 1 . Summary according to site of the time period during which data collection 

occurred and the percent and number of months for which data were collected 
on the landing of marine turtles on the Caribbean coast of Nicaragua. 



Site of Data 
Collection 


Time Period 
(Duration of Period) 


Percent of Months Data Collected 
(Number of Months ) 


Region Autonoma del Atlantico Norte 


Awastara 


February 1994-April 1997 
(39 months) 


74.4 
(29) 


Dakra 


February 1994-April 1997 
(39 months) 


74.4 
(29) 


Puerto Cabezas ab 


May 1991 -April 1997 
(72 months) 


80.6 
(58) 


Sandy Bay b 


May 1992-April 1997 
(60 months) 


83.3 
(50) 


Region Autonoma del Atlantico Sur 


Rio Grande Bar 


April 1991 -December 1996 
(69 months) 


66.7 
(46) 


Sandy Bay Sirpi c 


January 1991 -December 1996 
(72 months) 


88.9 
(64) 


Set Net 


July 1994-December 1996 
(30 months) 


100 
(30) 


Tasbapaune 


November 1993 -December 
1996 (38 months) 


94.7 
(36) 



a Source of data for 1991 : Cecil Clark, Puerto Cabezas, Nicaragua. 
b Source of data for 1992 and 1993: Caribbean Conservation Corporation. 
c Source of data for 1991-1993: Centro de Investigaciones y Documentation de la Costa 
Atlantica (CIDCA), Bluefields, Nicaragua. 



38 
Data Analysis 

Because the turtling grounds in the RAAN and RAAS are separated by 
approximately 220 km of ocean, data were not combined for these two regions. Data 
were analyzed either at the regional or community levels. Mean green turtle "Net 
Capture Per Unit Effort" (N-CPUE) was calculated for each community and region. For 
each trip, the N-CPUE was calculated using the following parameters: 1) "Days" - 
number of days turtling, 2) "Nets" - number of nets used, 3) "Turtles" = number of green 
turtles captured, and 4) "Net-Days" were calculated as "Nets" * "Days"; thus N-CPUE - 
"Turtles" * "Net-Days". Informal interviews with turtlers, indicated that turtle nets are 
approximately the same length, depth, and mesh size. 

Tasbapaune was the only community that reported the capture of green turtles by 
both entanglement nets and harpoons. Thus, data collected in Tasbapaune were used to 
compare the relative effectiveness of nets and harpoons for capturing turtles. In order to 
make this comparison, I devised a more general index of CPUE (G-CPUE) for each trip 
using the following parameters: 1) "Days" - number of days turtling, 2) "Persons" - 
number of turtlers, 3) "Person-Days" - "Persons" * "Days"; thus G-CPUE = "Turtles" + 
"Person-Days". 

All statistical analyses were conducted using SAS software (SAS Institute, Inc. 
1989). Univariate procedures were used to determine if distributions approximate 
normality and a t-test was used to test for equality of variances. When assumptions for 
parametric analyses were not met, non-parametric tests were used. Means ± 1 S.D. are 
presented. 



39 

Results 

Turtlers and Li vi ng Conditions onJhe TurtlingJiounds 

Turtlers are male, usually older than 12 years of age, although younger boys can 
accompany turtlers and assist in preparing food, tending the fire, cooking, cleaning, and 
guarding the living quarters. Living conditions on the turtling grounds differ between the 
RAAN and RAAS. In the RAAS, fishers (including men from all fishing activities 
except for mechanized shrimp boats) have constructed semi-permanent structures on 
several of the numerous coralline cays. In the RAAN, however, offshore cays are 
covered with mangroves and are not habitable. In the RAAN, fishers eat and sleep on 
their boats or spend the night in casitas (shelters constructed over shallow water from 
mangrove poles, wood planks, palm thatch, and corrugated tin). On the boats, food is 
cooked over wood fires contained in a metal kettle and fishers sleep on the floor. 

Imns4JOJlation^an±CapJin-eJVl£thQds 

In the RAAN, turtlers use wood-planked sail boats, referred to locally as "dories". 
Dories are approximately 9 m long with a depth of 1 m from the gunwale to the boat floor 
and approximately 1 .8 m at the widest point. They are constructed from hand-sawn 
planks of hardwood and powered by a main sail and jib. In the RAAS, turtlers that set 
nets use boats powered by 10-15 hp outboard motors to reach the turtling grounds, 
however, once they have arrived oars are used to set the nets and move between net-sets. 
Outboard motor boats used for turtling are approximately 9 m long, 0.6 m deep, and 0.6 
m wide between the gunwales at the widest point. Turtle harpooners use "cayucos", 



40 
which are dug-out canoes powered by sail and paddles. Cayucos are approximately 4 m 
in length and 0.8 m deep. 

In the RAAN, a fishing trip is usually focused on only one resource, however 
lobster divers also capture turtles, and harvest conch opportunistically. In the RAAS, a 
fishing trip is not resource specific. During a single trip the crew could set nets for 
turtles, dive for lobster, set lobster pots, and fish for shark. It was not possible to 
determine the number of active turtle boats per community in either the RAAN or RAAS 
because boats can be 1) used to harvest different resources from week to week, 2) under 
repair or construction, 3) rented out to a neighboring community, or 4) renamed once the 
boat is repaired or repainted. 

In both the RAAN and RAAS, green turtles are captured primarily with 
entanglement nets. However, turtlers in Set Net and Tasbapaune (RAAS) continue to 
strike turtles with harpoons. Entanglement nets are constructed from No. 18 nylon twine 
and are from 21 to 27 m long and approximately 7.5 m deep, with a 40 to 47-cm bar mesh 
size. Discarded flotation material found on the beach is strung on the headline and pieces 
of coral, harvested from the reefs, are tied-in to the footline of the net to maintain it 
vertical in the water column. A larger piece of coral is used as an anchor. Nets are set 
during the day, over reefs or coral outcroppings, where green turtles are known to return 
after having foraged on grassbeds throughout the day. At night, when an animal rises to 
the surface to breath it entangles in the net. Rarely is more than one turtle captured in a 
net at a time. Turtles rarely die in the nets because they are able to rise to the surface 
while entangled in the net and breath throughout the night. In the early morning, nets and 



41 
any captured turtles are retrieved. Flippers are restrained by binding together each 
anterior flipper with a posterior flipper with twine passed through a slit made in the distal 
portion of each flipper. In the RAAN, animals are stored on their carapace (upside down) 
in the bottom of the dory until the end of the trip. In the RAAS, animals are stored in 
turtle crawls, or on their carapace on the cays for the duration of the fishing trip. Turtle 
crawls are pens enclosed by mangrove poles set vertically in shallow water. Animals are 
allowed to move freely within them. 

Harpoons are constructed with a mahogany or palm wood shaft approximately 3 
m in length. Inserted into one end of the shaft is a removable, triangular, 3 -barbed point 
approximately 5.5 cm in length made from a metal file. The point is attached to a rope 
and at the other end of the rope is attached a wooden float. The shaft of the harpoon can 
also be attached to the rope. Two-man crews, a "striker" and a "captain", search for 
turtles early and late in the day. The striker poses on the bow of the boat ready to strike 
any turtle that surfaces within their range, approximately 12 m (D. Castro pers. com.). 
When a turtle is spotted the striker throws the harpoon, releasing the shaft and lodging the 
point in the carapace causing the point to detach from the wooden shaft. The captain 
quickly paddles the boat so that the striker can retrieve the float and shaft. The rope and 
turtle are hauled into the boat. 

Although green turtles are the focus of the turtle fishery other species are 
sometimes captured. Hawksbill, loggerhead {Caretta caretta), and leatherback 
(Dermochelys coriacea) turtles are captured incidentally in nets set for green turtles. 
Hawksbills are also captured by harpoon, and by hand when diving for lobster. 



42 

Capture Effort 

Spatial and t emporal com parison of enta nglement nets 

From December 1995 to December 1996, RAAS turtlers captured more than twice 
as many green turtles/net-day as RAAN turtlers (x N-CPUE = 0.26 ± 0.17 in the RAAS 
and 0.12 ± 0.08 in the RAAN; Wilcoxon rank-sums, P < 0.0001). The RAAS turtlers 
spent fewer days turtling, used fewer nets, and captured more turtles/trip then RAAN 
turtlers (Table 2.2). By community, the highest x N-CPUE in the RAAN (0.14 ± 0.08 for 
Sandy Bay) is similar to the lowest x N-CPUE in the RAAS (0.13 ± 0.07 for Rio Grande 
Bar) (Table 2.2). 

Temporal change in mean monthly N-CPUE was analyzed for all sites combined 
in the RAAN and RAAS separately, and for the community of Sandy Bay Sirpi, RAAS. 
In the RAAN, mean monthly N-CPUE was calculated from December 1995 to April 1997 
(17 mo) and in the RAAS, from December 1995 to December 1996 (13 mo). By region, 
there was no correlation between mean N-CPUE and month, and neither slope was 
significantly different from zero (RAAN, P = 0.36, r = 0.03; RAAS, P = 0.85, r = - 0.06). 
For Sandy Bay Sirpi, mean monthly N-CPUE was calculated from January 1991 to 
December 1996 (data are available for 48 mo of the 72 mo period). There is a weak 
correlation between mean N-CPUE and month, however, the slope is not significantly 
different from zero (P = 0.22, r = 0.37). 












43 



Table 2.2. Comparison of green turtle, Chelonia mydas, capture effort using 

entanglement nets by community and combined for the Region Autonoma del 
Atlantico Norte (RAAN) and Region Autonoma del Atlantico Sur (RAAS), 
Nicaragua from December 1995 to December 1996. Mean ± 1 S.D. is 
followed by range and sample size. Means were calculated per trip. 









Days 






Location 


Turtles 


Nets 


Turtling 


Net-Days* 


N-CPUE b 


RAAN 












Awastara 


10.6 ±6.0 


17.8 ±4.4 


5.5 ±2.4 


99.7 ±51.4 


0.13 ±0.09 




1-27 


10-30 


1-14 


13-270 


0.02- 0.50 




120 


117 


120 


117 


117 


Dakra 


5.3 ±3.5 


20.3 ± 3.4 


3.9 ± 1.6 


79.4 ± 37.6 


0.07 ± 0.04 




1-20 


15-36 


1-8 


27 - 200 


0.01-0.23 




80 


80 


80 


80 


80 


Sandy Bay 


13.9 ±6.7 


25.9 ±4.0 


4.2 ± 1.4 


108.8 ±39.1 


0.14 ±0.08 




2-40 


4-34 


1 -8 


16-224 


0.02 - 0.63 




124 


120 


124 


120 


120 


Combined 


10.6 ±6.7 


21.5 ±5.4 


4.6 ±2.0 


98.0 ±45.0 


0.12 ±0.08 




1 -40 


4-36 


1-14 


13-270 


0.01 -0.63 




324 


317 


324 


317 


317 


RAAS 












Rio Grande Bar 


28.4 ±21.5 


41.3 ±13.9 


5.7 ± 1.6 


242.4 ± 116.8 


0.13 ±0.07 




4-96 


7-58 


3-12 


21-660 


0.03 - 0.29 




40 


40 


40 


40 


40 


Sandy Bay Sirpi 


9.2 ±5.1 


18.8 ±4.5 


3.1 ±1.3 


59.7 ±31.5 


0.19± 0.15 




0-22 


8-30 


1 -8 


12 - 200 


0-1.05 




123 


119 


120 


118 


118 


Set Net 


5.2 ±5.1 


10.6 ±2.7 


2.3 ±0.8 


25.3 ± 12.6 


0.22 ±0.16 




1-30 


5- 16 


1 -4 


9-60 


0.06 - 0.75 




46 


44 


46 


44 


44 


Tasbapaune 


13.9 ±3.9 


15.1 ±4.5 


2.9 ± 1.0 


43.8 ± 19.1 


0.36 ±0.13 




3-24 


8-30 


1-6 


10- 108 


0.13-0.91 




167 


165 


167 


165 


165 


Combined 


12.8 ± 10.2 


18.6 ± 10.3 


3.2 ± 1.4 


68.3 ± 76.0 


0.26 ±0.17 




0-96 


5-58 


1 -12 


9-660 


0- 1.05 


a \r.i I-'* / t-> • ,-» 


376 


368 


373 


367 


367 



b Net Capture per Unit Effort = (Number of turtles / Trip) / (Net-Days / Trip); mean green turtle N-CPUE is 
significantly different between the RAAN and RAAS (Wilcoxon rank-sums, P < 0.0001). 



44 
Harpoon use 

Set Net and Tasbapaune are the only two communities where harpoons were 

reportedly still in use. Between July 1994 and December 1996, Set Net reported the use 

of harpoons for only two turtling trips, therefore data on the capture effort of turtles with 

harpoons will be analyzed only for Tasbapaune. From December 1995 to December 

1996 (13 mo), harpoons were used during 55 turtling trips. The mean G-CPUE was 2.7 ± 

0.9 (Table 2.3). 



Table 2.3. Comparison of the efficiency of harpoons and entanglement nets as methods 
for capturing green turtles, Chelonia mydas, by the community of Tasbapaune, 
Nicaragua from December 1995 to December 1996. Mean ± 1 S.D. is 
followed by range and sample size. Means were calculated per trip. 



Capture 
Method 


Turtles 


Persons 


Days Turtling 


Person-Days 8 


G-CPUE b 


Harpoons 

Nets 


5.6 ± 1.8 
2- 12 

55 

13.9 ±3.9 

3-24 

167 


2.0 ± 0.0 

2-2 
55 

3.0 ±0.5 
1 -4 
166 


1.0 ±0.2 

1 -2 

55 

2.9 ± 1.0 
1-6 
167 


2.1 ±0.4 

2-4 

55 

8.6 ±3.3 

3-20 

166 


2.7 ±0.9 
1.0-6.0 

55 

1.8 ±0.8 
0.7-6 

166 



Person-Days / Trip = (Number of persons / Trip) (Number of days turtling / Trip). 
b G-CPUE = (Turtles captured / Trip) / (Person-Days / Trip); mean green turtle G-CPUE is significantly 
different between the use of harpoons and nets (ANOVA, P < 0.0001). 

Harpoons and entang lement net s comp ared 

Since Tasbapaune turtlers did not use harpoons and nets during the same turtling 
trip, the effectiveness of netting and harpooning turtles can be compared statistically. 
From December 1995 to December 1996 (13 mo), the G-CPUE was significantly higher 
using harpoons (2.7 ± 0.9) than nets (1.8 ± 0.8; ANOVA, F, 219 = 60.7, P < 0.0001). 



45 
However, because netters spent nearly three times as many days turtling per trip than 

harpooners they captured more than twice as many turtles per trip (Table 2.3). 

CapiureiLQcaliQnsL^Region Autonoma del AtlanticoJ4orte_(RAAN) 

Between May 1992 and April 1997 (60 mo), a total of 66 capture locations for 
green turtles were recorded for the RAAN. Capture locations are places where turtlers 
claim to capture turtles with either nets or harpoons. The approximate surface area of 
capture locations range from 0.1 km 2 to 6.5 km 2 . Hawksbills were captured at 23 of the 
66 (34.8%) capture locations between December 1993 and April 1997 (41 mo), and 
loggerheads at 27 of the 66 (40.9%) capture locations between September 1994 and April 
1997 (32 mo). 

A total of 41 green turtle capture locations were reported by turtlers from 
Awastara, Dakra, Sandy Bay, and Puerto Cabezas for the same period (February 1 994 to 
January 1995, and December 1995 to April 1997, 29 mo). Hawksbills were captured at 
20 (48.8%) and loggerheads at 25 (61.0%) of these 41 capture locations. The greatest 
percentage of green turtles (40.5%, n - 4,702), hawksbills (26.9%, n = 21), and 
loggerheads (39.9%, n = 252) were captured at Witties. An additional 27.6% (n = 174) of 
loggerhead captures occurred at Leimarka. Each of the remaining capture locations 
produced less than 1 1% of the turtles captured for the three species. Only trips with no 
more than one capture location reported were included in these analyses. See Appendix 
A for a detailed compilation of RAAN capture locations for each species. 



46 
The RAAN communities overlapped in their use of capture locations. Twenty- 
one of 41 (51.2%) capture locations were used by more than 1 of the 6 communities 
(including data collected from the communities of Krukira, Pahra, and Walpasiksa when 
they landed their turtles at Puerto Cabezas) and 6 (14.6%) capture locations were used by 
4 or 5 communities. None of the capture locations were used by all six communities. Of 
the 19 (46.3%) capture locations used by only 1 community, 1 1 (26.8%) locations were 
used exclusively by Sandy Bay, 6 (14.6%) exclusively by Awastara, 2 (4.9%) exclusively 
by Dakra, and 1 location was used only by Walpasiksa (Appendix A). 

Capture Locations; Region Autonoma del Atlantico Sur (R AAS) 

Between January 1991 and December 1996 (72 mo), a total of 77 capture 
locations for green turtles were recorded for the RAAS. From August 1994 to December 
1996 (29 mo), hawksbills were captured at 30 (39.0%) and loggerheads at 24 (31.2%) of 
the 77 capture locations. However, a large proportion of animals for each species was 
captured from a small proportion of the capture locations. 

There was nearly complete partitioning of the turtling grounds between the four 
RAAS communities. Turtlers from Rio Grande Bar and Sandy Bay Sirpi shared three 
capture locations and turtlers from Set Net and Tasbapaune shared only one capture 
location. Rio Grande Bar and Sandy Bay Sirpi did not share any capture locations with 
Set Net or Tasbapaune. Because there was almost no overlap in the use of the 77 capture 
locations among the RAAS turtling communities results for each community are 



47 
presented separately. See Appendix B for a detailed compilation of RAAS capture 
location data for each community and species. 

Rio Grande B ar. For 46 mo, between April 1991 and December 1996, 24 green 
turtle capture locations were recorded. The majority of green turtles (53.8%, n = 3,027) 
were captured at three locations (Half-way, Vietnam, and Karmutra Banks). The 
remaining 21 capture locations each yielded less than 8% of the green turtles captured by 
Rio Grande Bar turtlers. Hawksbills were captured at eight (33.3%) and loggerheads at 
six (25.0%) of the 24 capture locations reported by Rio Grande Bar. Half-way Bank 
yielded the greatest percentage of hawksbills (25.0%, n = 3), whereas, De Tronco yielded 
the greatest percentage of loggerheads (40.0%, n = 4). 

Sandy Bayiiirpi. For 64 mo, between January 1991 and December 1996, 34 
green turtle capture locations were recorded. Three locations (Wainwin, South Schooner, 
and Half- Way Bank) accounted for 34.6% (n = 1,709) of the green turtles captured. The 
remaining 31 capture locations each yielded less than 8% of the green turtles captured by 
Sandy Bay Sirpi turtlers. Hawksbills were captured at 9 (26.5%) and loggerheads at 8 
(23.5%) of the 34 capture locations reported by Sandy Bay Sirpi. Three locations, 
Hawksbill Bank, Halfway Bank, and Lousiksa accounted for 72.3% (n = 26) of the 
hawksbills captured and two locations, Family Shoal and Diamond Spot, accounted for 
64.3% (n = 18) of the loggerheads captured. 

SeLNet. During the 30 mo period from July 1994 to December 1996, 7 green 
turtle capture locations were recorded. One location, Fowlshit Bank, accounted for 
64.2% (n = 488) of the green turtles captured. Hawksbills were captured at 5 (71.4%) and 



48 
loggerheads at 3 (42.9%) of the 7 capture locations. Long Reef accounted for 50.0% (n = 
9) of the hawksbills captured and together with Fowlshit Bank accounted for 95% (n - 
19) of the loggerheads captured. 

lashapaune. For 36 mo, between November 1993 and December 1996, 14 green 
turtle capture locations were recorded. Four locations (Haulover, Rivas, Buscan, and 
Middle Banks) accounted for 71 .6% (n = 4,392) of the green turtles captured. The 
remaining 10 locations each yielded less than 9% of the green turtles captured by 
Tasbapaune turtlers. Hawksbills were captured at 9 (64.3%) and loggerheads at 7 
(50.0%) of the 14 capture locations. One location, Haulover Bank, accounted for 30.8% 
(n = 20) of the hawksbills captured. The capture of loggerheads was more evenly 
distributed, with 3 of the 7 capture locations each accounting for between 23% and 32.5% 
of the total loggerhead captures. 

Use and Human DisMbutiorLof Harvested Turtles 
Green turtles 

Green turtle meat is traditionally consumed by humans. It is either used for 
subsistence by the turtlers, their families and friends, or sold in local and regional 
markets. More recently, the meat is also used as bait in lobster pots and for shark fishing. 
Turtles are transported to markets by the turtlers or purchased from the turtlers at sea or in 
their communities and transported to other markets by the buyer. 

Region_Autonomajiel AtlanticoJNorte^RAAN). Green turtles were distributed 
among at least 1 1 local and regional markets between November 1993 and April 1997 (42 



49 

mo). These markets are located as far north as Iralaya, Honduras and as far south as 

Bluefields and Corn Island (Figure 2.1). The relative amounts of meat consumed within 
and outside the turtlers community of residence differed between the three turtling 
communities. For the period from February 1994 to January 1995, and from December 
1995 to April 1997 (29 mo), for which monthly data collection occurred for all three 
communities, Awastara turtlers sold the majority of their green turtles (85.2%) outside 
their community of residence, whereas, the majority of turtles harvested by Sandy Bay 
(84.1%) and Dakra (60.9%) were consumed in the turtlers community of residence (Table 
2.4). Less than 5.5% of the turtles harvested by each community were consumed during 
turtling trips (Table 2.4). 

Of the green turtles sold to other markets, 82.0% (n = 5,895) were sold in the 
commercial center of Puerto Cabezas. The remaining 18.0% (n - 1,291) were sold 
among at least nine other markets (Table 2.4). A small amount of turtles sold by 
Awastara (1.5%) and Dakra (2.1%) were sold to the turtling community of Sandy Bay. 

Reg i on Auton omajiel AtlantkoAir (RAAS). Green turtles were distributed 
among at least 15 local markets between January 1991 and December 1996 (72 mo). 
These markets are located between Sandy Bay Sirpi and Corn Island (Figure 2.1). For 
the period from January to December 1996 (12 mo), for which monthly data collection 
occurred for all four communities, Rio Grande Bar (89.0%), Sandy Bay Sirpi (60.5%), 
and Set Net (61.1%) turtlers sold the majority of their green turtles outside their 
community of residence. Tasbapaune, however, consumed the majority (71.5%) of the 



50 

Table 2.4. Number and (percent) of green turtles, Chelonia mydas, by location of 

consumption for three Region Autonoma del Atlantico Norte (RAAN) turtling 
communities from February 1 994 to January 1 995 and December 1 995 to 
April 1997 (29 mo). All markets are located within Nicaragua unless 
otherwise indicated. 





RAAN TURTLING COMMUNITIES 




Location of Consumption 


Awastara 


Dakra 


Sandy Bay 


Total 


Community 


774 


1,022 


3,351 


5,147 




(10.7) 


(60.9) 


(84.1) 


(39.9) 


Other Markets 










Bihmuna 





63 


5 


68 




(0) 


(3.8) 


(0.1) 


(0.5) 


Bluefields 


174 








174 




(2.4) 


(0) 


(0) 


(1.4) 


Cabo Gracias a Dios 





71 


23 


94 




(0) 


(4.2) 


(0.6) 


(0.7) 


Corn Island 


382 


20 


15 


417 




(5.3) 


(1.2) 


(0.4) 


(3.2) 


Iralaya, Honduras 





41 


2 


43 




(0) 


(2.4) 


(0.1) 


(0.3) 


Koom 








10 


10 




(0) 


(0) 


(0.3) 


(0.1) 


Puerto Cabezas 


5,215 


364 


316 


5,895 




(72.2) 


(21.7) 


(7.9) 


(45.7) 


Rio Coco 








8 


8 




(0) 


(0) 


(0.2) 


(0.1) 


Sandy Bay 


107 


35 





142 




(1.5) 


(2.1) 


(0) 


(LI) 


Sold on cays a 


202 





48 


250 




(2.8) 


(0) 


(1.2) 


(1.9) 


Unknown 


72 


13 





85 




(1.0) 


(0.8) 


(0) 


(0.7) 


Turtling Trip 


297 


48 


207 


552 




(4.1) 


(2.9) 


(5.2) 


(4.3) 


Not Consumed (died) 


3 








3 




(0.04) 


(0) 


(0) 


(0.02) 


Total 


7,226 


1,677 


3,985 


12,888 


a Sold to Colombian, Cuban, Honduran, and Nicaraguan 


commercial fish 


ing boats for human c< 


)nsumption. 



and lobster trap and shark bait. 



51 
turtles harvested by their turtlers. Less than 6.5% of the turtles harvested by each 
community were consumed during turtling trips (Table 2.5). 

Of the green turtles sold to other markets, 67.4% (n = 1,571) were sold in the 
commercial center of Bluefields. The remaining 32.6% (n = 760) were sold among nine 
other markets (Table 2.5). Rio Grande Bar sold 15.2% (n = 144) of the turtles it sold to 
other markets to the turtling community of Sandy Bay Sirpi. 

I^mpojal change_ULhuman distribution of harvest ed turt les. The human 
distribution of harvested green turtles was compared between years for five turtling 
communities using a Chi-square test. Data were compared between 1994 and 1996 for 
Awastara, Dakra, Sandy Bay, and Sandy Bay Sirpi; and between 1995 and 1996 for 
Tasbapaune. There was a significant difference in the human distribution of harvested 
green turtles from one year to the next for each turtling community (Chi-square test, P < 
0.001, Table 2.6). From 1994 to 1996, for the three RAAN communities (Awastara, 
Dakra, and Sandy Bay), there was an increase in the proportion of animals consumed in 
the community, whereas, for the two RAAS communities (Sandy Bay Sirpi and 
Tasbapaune) there was an increase in the proportion of animals sold outside the 
community. For four of the five communities, the percent of green turtles consumed 
during the turtling trip increased from 1994 to 1996, however, this category still 
represents a small proportion (< 6.6%) of the fate of harvested green turtles (Table 2.6). 
Hawkshill turtles 

Hawksbills are harvested for their scutes. The meat can be consumed by the 
turtler and his family, given to others for consumption, or discarded. From January 1991 



52 



Table 2.5. Number and (percent) of green turtles, Chelonia mydas, by location of 

consumption for the Region Autonoma del Atlantico Sur (RAAS) turtling 
communities from January 1996 to December 1996 (12 mo). All markets are 
located within Nicaragua. RGB = Rio Grande Bar, SBS - Sandy Bay Sirpi, 
SN = Set Net, TA = Tasbapaune. 





RAAS TURTLING COMMUNITIES 




Location of Consumption 


RGB 


SBS 


SN 


TA 


Total 


Community 


97 


418 


68 


1,762 


2,345 




(9.1) 


(37.1) 


(32.7) 


(71.5) 


(48.2) 


Other Markets 












Bluefields 


603 


572 


5 


391 


1,571 




(56.6) 


(50.6) 


(2.4) 


(15.9) 


(32.3) 


Cocabilla 








17 





17 




(0) 


(0) 


(8.2) 


(0) 


(0.3) 


Corn Island 


80 


30 





84 


194 




(7.5) 


(2.7) 


(0) 


(3.4) 


(4.0) 


Haulover 








3 





3 




(0) 


(0) 


(1.4) 


(0) 


(0.1) 


Kukra Hill 





10 








10 




(0) 


(0.9) 


(0) 


(0) 


(0.2) 


Marshall Point 








1 





1 




(0) 


(0) 


(0.5) 


(0) 


(0.02) 


Orinoco 











57 


57 




(0) 


(0) 


(0) 


(2.3) 


(1.2) 


Pearl Lagoon 








101 


9 


110 




(0) 


(0) 


(48.6) 


(0.4) 


(2.3) 


Sandy Bay Sirpi 


144 











144 




(13.5) 


(0) 


(0) 


(0) 


(3.0) 


Sold on cays a 


121 








2 


123 




(11.4) 


(0) 


(0) 


(0.1) 


(2.5) 


Unknown 





71 





30 


101 




(0) 


(6.3) 


(0) 


(1.2) 


(2.1) 


Turtling Trip 


20 


26 


13 


130 


189 




(1.9) 


(2.3) 


(6.3) 


(5.3) 


(3.9) 


Not Consumed (died) 











1 


1 




(0) 


(0) 


(0) 


(0.04) 


(0.02) 


Total 


1,065 


1,127 


208 


2,466 


4,866 


a Sold to Honduran and Nicaraguan 


commercial 


fishing boats. 









53 



Table 2.6. Human distribution of harvested green turtles, Chelonia mydas, compared 
between years for five turtling communities. Percent of year's total is 
followed by (number) of green turtles. Years within a community were 
compared using a Chi-square test. 



DISTRIBUTION OF HARVESTED GREEN TURTLES 

Consumed in Sold Outside Consumed 
Community Year Community Community on Trip P 

1994 4.5(132) 94.7(2,771) 0.8(23) 

Awastara ■ < 0.001 

1996 14.5(440) 78.8(2,385) 6.6(201) 



1994 45.6(453) 53.6(532) 0.8(8) 

Dakra < 0.001 

1996 89.4(330) 4.9(18) 5.7(21) 



1994 78.6(1,279) 18.2(296) 3.3(53) 

Sandy Bay < 0.001 

1996 88.9(1,428) 4.8(77) 6.3(101) 



Sandy Bay 1994 48 " 7 (384) 513 ( 404 > ° < Q > 

Sirpi 

1996 37.1(418) 60.6(683) 2.3(26) 



< 0.001 



1995 79.9(127) 9.4(15) 10.7(17) 
Tasbapaune ■ < 0.001 

1996 71.4(1,759) 23.3(573) 5.3(130) 



through 1996, at least 272 hawksbills were captured in the RAAN and RAAS (see 
Chapter 3 and Appendix F). Although most captured hawksbills are killed, key 
informants reported that sometimes scutes are removed from live animals by leaving 
them in the hot sun, holding the carapace over a fire, or peeling off the scutes with the hot 
blade of a knife. The live, scuteless animal is then released. Coastal inhabitants reported 



54 
seeing marked animals with regenerated scutes, however, the regeneration of scutes has 
not been verified nor have mortality rates from this practice been quantified. Scutes are 
dried and stored until a buyer is found. Local artisans make various types of jewelry 
from hawksbill shell which can be found for sale throughout the country including in 
commercial centers along the coast, at the international and national airports, and at 
tourist markets in Managua. 
Loggerhead turtles 

Loggerhead turtles are either released from the nets unconscious, killed and 
discarded, or harvested for shark and lobster trap bait; the meat is not consumed because 
of its strong flavor. Turtlers kill or club loggerheads unconscious to facilitate removal 
from the nets, and to avoid the risk of being bitten. Mortality is high even among those 
animals that are discarded while still alive because clubbed loggerheads are usually 
discarded prior to regaining consciousness and most probably drown. From January 1994 
through 1996 , at least 825 loggerheads were reported captured (see Chapter 3 and 
Appendix F). 

Discussion 

Capture Methods 

The capture methods described by Nietschmann (1972, 1973, 1974) and Weiss 
(1975, 1976) are relatively unchanged except that outboard motors are now used by 
RAAS net-turtlers, but not by harpoon-turtlers. Outboard motors are a relatively recent 
addition and are a result of negotiations to end the civil war in the mid-1980s (D. Castro 



55 
pers. com.). The RAAS fishers were provided with loans from the central government. 
In the RAAN, however, turtlers continue to use sailing dories. Outboard motors are used 
in the RAAS to travel between the mainland and turtling grounds, but not to aid in the 
capture of turtles. Their use decreases travel time to and from the turtling grounds, but 
because motors are not used to set or retrieve nets the use of outboard motors in the 
RAAS does not account for the greater net capture rate. 

Entanglement nets is the principal method in use today to capture turtles. Nets 
were introduced to the Miskitu Indians by Cayman Island turtlers sometime before 1915 
(Conzemius 1932). Prior to their introduction, Miskitu Indians used harpoons. Today, 
only two of the Miskitu and Miskitu Indian/Creole mix communities (Tasbapaune and 
Set Net) continue to use harpoons. In the late 1960s, the use of both nets and harpoons 
by Tasbapaune turtlers was reported but no mention was made as to the relative 
prevalence of either method (Nietschmann 1972, 1973). At least as early as 1971, 
harpoons were no longer used by Sandy Bay Sirpi turtlers (Weiss 1975) and this pattern 
continues today. 

The use of nets provides an advantage for neophyte turtlers, however, the 
harvesting of coral to anchor-down the nets could be detrimental to the environment. 
Because net-setters work in crews of 3 to 6 men, an inexperienced turtler has the 
advantage of working with more experienced turtlers and will be successful at capturing 
turtles and thus profit immediately. The opportunity to learn from more experienced 
turtlers while sharing in the profits derived from their success could explain the 
prominent use of nets today. One of the drawbacks to the use of nets is the indiscriminate 



56 
harvest of coral for use as weights on the footline and to anchor the net. Studies are 
needed to quantify the amount of coral harvested and to evaluate the extent of damage to 
the reef. 

Historically, harpoons were the sole method of capture, however, today, they are 
seldom used. Their decreased use could reflect the need to be more skillful in order to be 
successful. Harpooners probably spend more time practicing and need more patience to 
become proficient, and the technique necessitates good communication and cooperation 
between the striker and captain. Nevertheless, the increased investment in time needed to 
be a proficient harpooner can be worthwhile in the long-run because harpoons are a more 
efficient method of capturing turtles, at least during this study. However, Nietschmann 
(1973) reported nets were more efficient, although the basis for this conclusion is not 
given. 

Capture Efficiency 

On average, RAAN turtlers spend more days turtling and use more nets/trip but 
capture fewer green turtles than turtlers in the RAAS. The difference between the regions 
in the mean number of days spent turtling/trip is probably due to the distance of the 
turtling grounds to the communities and the mode of travel. The RAAN turtlers travel 
more than twice the distance than RAAS turtlers to reach most of their turtling grounds 
and they travel by sail-powered dories compared to the use of motorboats by RAAS 
turtlers. Because of the greater time invested by RAAN turtlers to reach the turtling 
grounds it's not surprising that they spend more days turtling/trip. 



57 
The higher net capture rate of green turtles in the RAAS could reflect either 
higher turtle density or better turtling skills by RAAS turtlers. Both regions of the 
country, however, have been turtling for several hundred years, have been exposed to 
similar outside influences and technology, and currently use the same netting technique. 
Therefore the observed difference in capture rates is more likely explained by a difference 
in green turtle abundance due to physiognomic and biotic habitat variation, turtle 
migration patterns, or exploitation rates during the recent past. Mortimer (1981) found 
that stomach contents of green turtles differed among several capture locations along the 
Nicaragua coast suggesting that floristic composition varied among locations. Other 
parameters, such as substrate type, current direction and flow rate, water depth and clarity 
could also influence capture efficiency. In addition, storms can cause local perturbations 
affecting habitat and subsequently sea turtle populations. Green turtles feed selectively 
on young blades of turtle grass, Thalassia testudinum, thereby, decreasing the proportion 
of lignin and increasing the proportion of protein consumed (Bjorndal 1980a). In 1988, 
Hurricane Joan struck the coast of Nicaragua near Bluefields (Roth 1992). Although no 
studies were conducted to identify changes that occurred to the offshore underwater 
habitats in the RAAS as a result of the storm, its possible that the disturbance caused by 
the hurricane stimulated new growth among the seagrass beds resulting in higher green 
turtle population densities. 

Secondly, funneling of turtles into a relatively narrow pathway as they migrate 
south towards the nesting beach at Tortuguero, Costa Rica could increase turtle density 
seasonally as turtles from the RAAN and farther north migrate south through the RAAS. 



58 
Turtles reportedly often use a longshore route when passing through Nicaraguan waters 
during breeding migrations, traveling along the coast in nearshore waters (Carr 1954). 
Therefore, in Nicaragua, when turtles use these longshore routes turtlers set their nets 
over the shallow, mud flats, referred to as a "mudset", located within 3 km of shore 
between Prinzapolka and Set Net point (see Figure 2.1, Carr 1954; Nietschmann 1973; 
Mortimer 1976, 1981). 

A third possibility is that exploitation levels in the two regions have differed 
during the recent past, thus affecting current resource abundance. In the RAAN, during 
the civil war, turtlers were only allowed to make trips to the offshore cays that originated 
from Puerto Cabezas. For the period 1985 to 1990 (during the Sandinista/Contra war), 
16,700 green turtles (x = 2,783 turtles/yr, S.D. = 681, range = 1,619 - 3,375, n = 6) were 
harvested from the RAAN and landed in Puerto Cabezas (Montenegro Jimenez 1992). 
For the RAAS, harvest levels of marine turtles during the war are not available, however, 
turtling activities were more severely decreased or suspended because of the large 
military presence and battles fought near the communities. Thus, the higher capture rate 
of turtles in the RAAS could be due to a higher density of turtles because of reduced 
harvest pressure during the war compared to the RAAN. 

Mean, monthly, N-CPUE in the RAAN, RAAS, and for Sandy Bay Sirpi does not 
indicate, at this time, that the abundance of turtles within the size range of animals 
harvested has declined during the study period. The trend in the N-CPUE for all three 
analyses indicates there has been no change in the number of green turtles captured/net- 
day. However, analyses were conducted over very short time periods (from 13 to 72 mo) 



59 
and could be too short to detect a change in the abundance of the foraging population. A 
problem with using CPUE to estimate stock abundance is that fishers go where the fish or 
turtles are and CPUE can remain high until the stock is seriously depleted, a situation 
described as hyperstability by Hilborn and Walters (1992). 

The N-CPUE for Sandy Bay Sirpi has increased 850% since the study conducted 
by Weiss (1975) in 1972/1973, assuming net length, depth, and mesh size have remained 
constant. Based on data provided by Weiss (1975), I calculated a mean of 0.02 
turtles/net-day captured for Sandy Bay Sirpi turtlers for a one-year period beginning in 
mid- 1972 compared to a mean of 0.19 ± 0.15 turtles/net-day calculated for the period 
December 1995 to December 1996 (this study). The low N-CPUE realized in 1972/1973 
could reflect declines in the turtle population resulting from the estimated 6,000 - 10,000 
animals harvested annually from the coast between 1969 and 1973. Current harvest 
levels for the coast are similar to those reported for the late 1960s and early 1970s. 
Although this harvest level has not been continuous since the 1970s, Sandy Bay Sirpi 
harvest levels have been relatively constant since at least 1991 (see Chapter 3). In 1990, 
the country ended a decade-long civil war during which the exploitation of natural 
resources by both nationals and foreigners was greatly reduced (Nietschmann 1995). The 
harvest of turtles in the RAAS may not be as intense and the number of turtlers may have 
decreased since the 1970s because today many men also fish for lobster and shark. 
Whereas, in 1972, Weiss (1976) reported the only other major source of income in Sandy 
Bay Sirpi was as temporary wage laborers on shrimp and fishing boats. 



60 
Capture Locations 

The 141 capture locations for marine turtles range in surface area from 0.1 km 2 to 
6.5 km 2 . Because of their vast size, each location has within it numerous sites where nets 
are set. Marine turtle capture sites are dynamic, with new sites identified and known sites 
abandoned due to low productivity. Turtlers identify potential new capture sites by 
looking for submerged rocks on sunny, clear days. Nets are set and if turtles are captured 
the site is given a name. According to the turtlers, each turtle uses several different 
"sleeping rocks". Because sites within capture locations can be temporarily 
unproductive, turtlers do not set their nets at the same site every day. Capture sites can 
also become unproductive for long periods, e.g., in December 1995, P. Hills, a Rio 
Grande Bar turtler, reported 13 unproductive capture sites. No information is available as 
to how long a capture site can remain unproductive. 

Partitioning of turtling grounds among the communities differs between the 
RAAN and RAAS. In the RAAN, communities overlap extensively in their use of turtle 
capture locations, whereas, in the RAAS, there is almost complete partitioning by the 
communities. The lack of partitioning in the RAAN is probably because the distance to 
the turtling grounds is approximately the same regardless from which community a trip 
originates. Geographically, the RAAN communities are located relatively close to each 
other but the turtling grounds are distant. In the RAAS, turtling grounds are located 
offshore of each community decreasing the need to overlap on the turtling grounds or 
travel farther than necessary. This partitioning of capture locations by community in the 
RAAS was recognized as early as 1972 (Weiss 1975). 



61 
In the RAAN, managing the use of capture locations should be discussed at a 
regional level with representation from each of the turtling communities. For example, 
one of 35 capture locations in the RAAN (Witties) provided a large percentage of the 
green (40.5%), hawksbill (26.9%), and loggerhead (39.9%) turtles captured. Therefore, if 
reduction in the use of this one capture location could be agreed upon by all RAAN 
turtlers a decrease in the capture rate of all three species could be realized. 

The fact that some communities overlap in their use of capture locations could 
facilitate enforcement. For example, compliance with regulations on the use of capture 
locations could be enhanced by intercommunity surveillance. Because the proportion of 
each community's harvest is not the same from each capture location, however, some 
form of compensation might have to be devised so that any hardships can be more 
equitably distributed among the communities. 

In contrast, the establishment of regulations governing the use of capture locations 
in the RAAS would best be approached on a community by community basis. Although 
selection and agreement of regulations on the use of capture locations could be easier to 
establish on a community by community basis, compliance and self-surveillance could be 
more difficult to achieve. Since turtles are not confined in their movements by 
community partitioning of capture locations, but probably move among the RAAS 
capture locations and possibly between RAAN and RAAS foraging areas it will also be 
important for the RAAS communities to develop a regional management plan, as well as, 
inter-regional agreements for the use of this shared resource. 






62 
Human Distribution of Harvested Turtles 

Approximately 50% of the green turtles captured are sold outside the turtlers 
communities of residence, both in the RAAN (55.7%) and the RAAS (48.0%). The 
percent of turtles distributed to outside markets varies greatly from one community to the 
next, from a low of 10.8% for Sandy Bay to a high of 89.0% for Rio Grande Bar. The 
decision to sell the harvest outside the community probably depends on the size of the 
community, purchasing power of the community, and the turtlers need to obtain money. 

Dakra, Sandy Bay, and Tasbapaune, communities with the largest number of 
inhabitants, consumed more than 60% of the green turtles harvested by their turtlers. In 

1994, the populations of Dakra and Sandy Bay were approximately 1,400 and 4,000 
inhabitants, respectively (Comision National Interinstitucional 1995). In 1996, 
Tasbapaune had approximately 3,200 inhabitants (R. Carlos pers. com.). In addition, the 
capacity of Sandy Bay inhabitants to consume turtles was apparently greater than the 
number of turtles harvested because they purchased 1.5% of Awastara's and 2.1% of 
Dakra' s turtle harvests. 

The ability of a community to purchase turtles is dependent on the communities 
overall purchasing power. The higher the median income in a community the more 
money available to purchase goods and services, including turtle meat. Beginning in 

1995, Sandy Bay and Dakra received assistance from private companies to enter into the 
lobster trap fishery (D. Castro pers. com.). This has probably increased the median 
income in each community. The increase in the percent of turtles consumed in Sandy 
Bay and Dakra from 1994 to 1996 is possibly a result of this additional source of income. 



63 
Rio Grande Bar, Awastara, Set Net, and Sandy Bay Sirpi consumed the smallest 
percent of their harvests in their communities, 9.1%, 10.7%, 32.7%, and 37.1%, 
respectively. Of these communities, Rio Grande Bar and Set Net had the fewest 
inhabitants, with approximately 150 and 200 inhabitants, respectively in 1996 (L. 
Churnside pers. com.; F. Thomas pers. com.). In contrast, Awastara and Sandy Bay Sirpi 
are large communities with approximately 1 ,200 inhabitants in 1 994 (Comision Nacional 
Interinstitucional 1995) and 1,100 inhabitants in 1995 (E. Smith pers. com.), respectively. 
Compared to Sandy Bay and Dakra, two other RAAN turtling communities, Awastara 
has fewer sources of income and although they increased their community consumption 
of turtle meat from 4.5% in 1994 to 14.5% in 1996 they still consume a relatively small 
proportion of their turtle harvest. 

The human distribution pattern of harvested turtles by Sandy Bay Sirpi is less 
easily explained. Although Sandy Bay Sirpi is one of the largest of the turtling 
communities it sold over 71% of its harvested turtles outside the community. However, it 
also purchased 13.5% of Rio Grande Bar's turtles. For Sandy Bay Sirpi, the incentive to 
sell a large majority of its green turtle harvest outside the community might be motivated 
by a higher price/lb of meat sold in the Bluefields market compared to a lower price for 
live turtles purchased from another turtling community. Turtle meat is sold in the 
communities for approximately 1/3 to 1/2 the price/lb of meat sold in the commercial 
centers (Lagueux unpubl. data). 

The proportion of the harvest sold outside the turtlers community of residence 
during this study is lower than the proportion sold to the turtle processing plants in the 



64 
early 1970s, for the two communities for which data are available. In 1971, Tasbapaune 
sold 66% of its harvest to the plants (Nietschmann 1972, 1973) compared to 23.3% of the 
harvest sold outside the community today. For a one-yr period, from 1972 to 1973, 
Sandy Bay Sirpi sold 81 .4% of its harvest to the plants (Weiss 1976) compared to 60.5% 
of the harvest sold outside the community today. 

These data probably underestimate the amount of trade occurring on the foraging 
ground themselves. Because of the expanse of the area and the number of boats fishing 
on Nicaragua's continental shelf there is a large potential for trade in sea turtles with 
other boats. Informants report that on the cays, turtles are purchased to feed the crews of 
fishing and lobster boats from San Andres Colombia, Cuba, Honduras, and Nicaragua, 
and also purchased for transport to the Cayman Islands and San Andres Colombia to be 
sold in their markets. More effort is needed to determine, for each species, the number of 
animals purchased for bait, purchased by fishing boats for food, and transported to other 
countries. 

Conclusions 

The patterns of human use of sea turtles in Nicaragua today are not much different 
than during the past several hundred years of resource use on this coast. Since prior to 
European contact, Miskitu Indians have harvested marine turtles from their coastal waters 
for personal use, to trade for other goods, and to sell for income with which to purchase 
other goods and services. Although the current harvest of marine turtles is no longer to 
supply international markets, the local and regional (within Nicaragua) demand for a 



65 
source of inexpensive protein and tortoiseshell could be just as devastating to the marine 
turtle foraging populations. As Frazier (1980) has noted, the issue is not whether the 
exploitation of a resource is "good" or "bad" but whether or not the resource can sustain 
harvest levels and patterns of resource use. 

Data presented in this chapter are needed for the establishment of a management 
plan for the Miskitu marine turtle fishery. These data are important to our understanding 
of current human use patterns of marine turtles and are beneficial in making management 
decisions. In addition, these data provide a basis with which to monitor changes in the 
fishery which may result from management actions or due to external forces. 



CHAPTER 3 
HARVEST RATES AND DEMOGRAPHICS OF MARINE TURTLES 



Introduct ion 

Throughout history the harvest of sea turtles and their eggs have occurred 
virtually wherever people and turtles coincide. Although the eggs of all species have 
been harvested, animals of the seven species have been exploited to varying degrees. 
Most harvests of marine turtles have targeted green turtles (Chelonia mydas) and 
hawksbills (Eretmochelys imbricata) (Hornell 1927; Ingle and Smith 1949; Carr 1954; 
Parsons 1956, 1962, 1972; Hirthand Carr 1970; Nietschmann 1972, 1973; Rebel 1974; 
Frazier 1975, 1979; Cato et al. 1978; Bjorndal 1982; Dodd 1982; King 1982; Milliken 
and Tokunaga 1987; Mortimer 1984; Meylan 1997a). Harvests of the olive ridley 
{Lepidochelys olivacea) (Carr 1967, 1972, 1979; Pritchard 1979; Frazier 1981), Kemp's 
ridley (Lepidochelys kempi) (Pritchard and Marquez 1973), loggerhead {Caretta caretta) 
(Brongersman 1982), and leatherback (Dermochelys coriacea) (Starbird and Suarez 1994; 
Suarez and Starbird 1995) have either occurred for a shorter duration or have been more 
localized. The endemic flatback turtle (Natator depressus) has played a limited role in 
marine turtle harvests in Australia (Bustard 1972). 

In Nicaragua, marine turtles have been harvested from beaches and offshore 
waters of the Caribbean coast by indigenous coastal inhabitants and foreigners for over 

66 



67 
400 years (Parsons 1962; Roberts 1965; Dampier 1968; Nietschmann 1973; Montenegro 
Jimenez 1992; Lagueux 1993). Four of the world's seven extant marine turtle species are 
found offshore on Nicaragua's vast continental shelf- greens, hawksbills, loggerheads, 
and leatherbacks. Nicaragua's coastal area provides foraging and developmental habitat 
for the largest green turtle foraging population in the Atlantic Ocean (Carr et al. 1978). 
Juvenile and adult turtles immigrate to Nicaragua's coastal waters from throughout the 
greater Caribbean. Green turtles also use these waters as a migratory pathway for travel 
to and from the nesting beach at Tortuguero, Costa Rica (Carr 1954). Juvenile and adult 
hawksbill turtles can be found foraging among offshore coral reefs and seagrass beds 
(Nietschmann 1973, 1981; Lagueux pers. obs.). The hawksbill is the only species that 
has been confirmed to nest on mainland beaches and offshore cays of Caribbean 
Nicaragua (Nietschmann 1973, 1981). Almost nothing is known about the use of 
Nicaragua's beaches and offshore waters by loggerheads and leatherbacks. Unconfirmed 
reports, however, indicate that green, loggerhead, and leatherback turtles nest 
infrequently on Nicaragua's mainland beaches (Bacon 1975; Carr et al. 1982; this study). 

In the Nicaragua fishery, the green turtle is the principal species targeted. 
Hawksbill turtles are harvested opportunistically whenever they are encountered. 
Loggerhead and leatherback turtles, although not targeted in the marine turtle fishery, are 
captured incidentally in nets set for green turtles. 

Historically, only rough estimates have been made on the magnitude of the 
Nicaragua marine turtle fishery (Lewis 1940; Ingle and Smith 1949; Carr 1954; Parsons 
1962; Nietschmann 1973; Weiss 1975) and demographics of harvested animals have 



68 
never been reported. Because Nicaragua's marine turtle fishery is legal and not 

clandestine, collecting data on the fishery and harvested animals is more easily 
accomplished. Data on the number of animals captured by species, and size and sex of 
harvested animals are needed to evaluate the impact of the fishery on marine turtle 
populations that occur within Nicaraguan waters, as well as, the greater Caribbean region. 
In addition, the sex ratio and size distribution of captured green turtles are probably 
indicative of the foraging population because there is no evidence that net capture 
methods are biased towards either sex or size, within the size range of animals captured in 
the fishery. These data are also important in regulating and monitoring resource use. 

In this chapter, I quantify the number of animals harvested by species per year and 
describe the size and sex of harvested animals. The magnitude of the harvest for each 
species is analyzed to determine seasonal and long-term trends. The size and sex ratio of 
harvested animals by species are determined to provide baseline information on the 
segment of each population impacted by the fishery, and to compare the demographics of 
harvested green turtles between regions of the coast. The size distribution of harvested 
female green turtles is compared to the size distribution of nesting females to determine 
the proportion of harvested animals that are smaller than reproductive size. A temporal 
analysis is conducted to determine if changes have occurred in the mean size of harvested 
animals. 



69 
Methods 



The turtling communities and commercial center where data were collected are 
described in Chapter 2. The initiation date for the collection of harvest data on each turtle 
species differed. Partial data on the harvest of green turtles from both the Region 
Autonoma del Atlantico Norte (RAAN) and the Region Autonoma del Atlantico Sur 
(RAAS) have been available at least since 1991 and are included in this study. Data 
collection on the harvest of hawksbills was initiated January 1991 in the RAAS and 
December 1993 in the RAAN. Data collection on the capture of loggerheads and 
leatherbacks was initiated January 1994 in the RAAS and September 1994 in the RAAN. 
For all species, data collected through April 1997 in the RAAN and December 1996 in 
the RAAS are included. 

In 1991, Cecil Clark, head of the marine turtle butchers cooperative recorded 
landings of turtles at Puerto Cabezas. From 1991 to 1993, the collection of harvest data 
in the communities of Rio Grande Bar and Sandy Bay Sirpi was conducted by the Centro 
de Investigaciones y Documentation de la Costa Atlantica (CIDCA). Beginning in April 
1992 in the RAAN and in November 1993 in the RAAS, I trained local data collectors. 
Supervision of data collection has been conducted by Denis Castro, my Miskitu Indian 
counterpart, and me. Selection and employment of data collectors are described in 
Chapter 2. 






70 
Ty pes of Harve st Data Collected 

Harvest and demographic data on marine turtles were recorded when a boat 
returned from a turtling trip. For each turtling trip, the following data were recorded: 1) 
turtlers community of residence, 2) date trip terminated, and 3) total number of turtles of 
each species captured. For as many individual turtles as possible, the following data were 
also recorded: 1) species, 2) plastron length (PL), and 3) sex. Plastron length was 
measured along the midline from the anterior junction of the skin and intergular scute to 
the posterior termination of the plastron midline with a 150-cm flexible tape measure. 
Although plastron length is not the preferred measurement taken among sea turtle 
biologists it was the most practical because animals are transported and stored upside 
down. Sex was based on the examination of external sex characteristics, i.e., tail length 
and the size and shape of the anterior flipper claws. 

During a preliminary study conducted from May 1992 to March 1993 in Puerto 
Cabezas and from May 1992 to December 1993 in Sandy Bay, the following turtle 
measurements were recorded: 1) minimum (notch-to-notch) curved carapace length 
(CLN), 2) minimum (notch-to-notch) straight carapace length (SLN), 3) body mass (WT), 
and 4) sex. A 150-cm flexible tape measure was used for all curved measurements and a 
127-cm tree caliper was used for all straight measurements. Minimum carapace lengths 
were measured along the midline from the anterior edge of the nuchal scute to the 
posterior termination of the midline to the nearest 0.1 cm. Body mass was determined to 
the nearest 2.5 lb with a 500-lb spring scale and converted to kilograms. 



71 
Calculation of Harvest Rates 

The annual harvest rates of marine turtles are minimum estimates because harvest 
data were not collected from every Miskitu Indian and Miskitu/Creole turtling 
community nor from any of the Rama Indian communities (see Chapter 2). In addition, 
not all turtles captured were necessarily reported to the data collectors and none of the 
turtles captured incidental to other fisheries were reported. Monthly harvest rates for 
each data collection site were calculated based on the numbers of turtles actually recorded 
and estimated to have been landed. For a variety of reasons, however, data were not 
collected during every month of the study period at all data collection sites (see Methods 
in Chapter 2). For those months for which data were not available, I estimated the 
monthly harvest rate based on known monthly harvest rates for each site, for each year. 
In 1995, data were collected for only two to three months in Awastara, Dakra, and Sandy 
Bay. Thus, I estimated the monthly harvest rates for each data collection site based on 12 
months of known harvest rates, 6 months prior and 6 months post the period of missing 
data. 

Care was taken not to include the same harvested animal more than once in the 
totals. Because, in the RAAN, turtle boats dock at more than one data collection site it 
was possible for animals to be recorded twice. To avoid overestimating the harvest rate, I 
excluded from the total, animals recorded at one site but sent to another site in which a 
data collector was employed. However, if turtles were sent to a site where no data 
collector was employed then these animals were included in the total. 



72 
Turtle Mor phometries 

A series of 1 1 body measurements were used to attempt to characterize 
morphological differences between male and female turtles foraging in Nicaragua. 
Because sea turtle biologists record any of eight different carapace lengths (Pritchard et 
al. 1983), it is difficult to make comparisons among studies. Therefore, regression 
equations were developed to predict the other measurements from minimum curved 
carapace (CLN). For green turtles, measurements were taken from a stratified random 
sample of animals landed at Puerto Cabezas between November 1993 and January 1995. 
Each month I attempted to measure a minimum of 40 harvested animals, 10 from each of 
the following four categories: "small" males, "large" males, "small" females, and "large" 
females. The cut-off between "small" and "large" was based on the size of the smallest 
nesting females at Tortuguero, Costa Rica in 1988 (Caribbean Conservation Corporation 
unpubl. data). Animals smaller than 89.8 cm minimum straight carapace length were 
categorized as "small". The sex of animals was verified when they were butchered (see 
Chapter 4). All hawksbills were measured whenever possible. No loggerheads or 
leatherbacks were measured because they are not landed at Puerto Cabezas. Any 
measurement that might have been affected by deformities or mutilations were excluded 
from the analyses. 

The 1 1 body measurements I recorded were the following: 1) minimum (notch- 
to-notch) curved carapace length (CLN), 2) minimum (notch-to-notch) straight carapace 
length (SLN), 3) maximum (tip-to-tip) curved carapace length (CLT), 4) maximum (tip- 
to-tip) straight carapace length (SLT), 5) plastron length (PL), 6) plastron to vent length 



73 
(VENT), 7) tail length (TAIL), 8) length of each anterior flipper claw (CLEN), 9) 

minimum basal diameter of each anterior flipper claw, 10) maximum basal diameter of 
each anterior flipper claw, and 1 1) body mass (WT). Maximum carapace lengths were 
measured from the most anterior to the most posterior projections of the carapace. Vent 
and tail lengths were measured from the posterior termination of the plastron midline to 
the center of the vent (VENT) and to the tip of the straightened tail (TAIL). Length of 
each anterior flipper claw was measured from the junction of the skin and claw to the tip 
of the claw along the outer curvature and the mean CLEN/turtle (xCLEN) was calculated 
from right and left measurements. Minimum and maximum basal diameters of each 
anterior flipper claw were measured with a dial caliper to the nearest 0.05 mm and used to 
calculate the basal area of each anterior flipper claw. Basal area was calculated using the 
formula for the area of an ellipsoid: 

A = izab 
where X is 3.14, a is one-half the shortest diameter, and b is one-half the longest 
diameter. Mean basal area of anterior claw/turtle (xCBASE) was calculated from right 
and left measurements. All other measurement are as previously described (see Types of 
Harvested Data Collected in Methods). A 127-cm tree caliper was used for straight 
carapace measurements. Unless otherwise stated, measurements were made with a 150- 
cm flexible tape measure. 



74 
ISex Identification of Green Turtles 

The ability of the Puerto Cabezas data collector to sex animals based on external 
characteristics was evaluated to determine the accuracy of the data obtained. He first 
sexed each animal externally, and I noted whether or not external sex characteristics were 
obvious (as described above). Sex was then verified based on gonadal examination of the 
butchered animals. Turtles were grouped into 2.5-cm size classes based on plastron 
length in order to identify the minimum plastron length at which an animal can be sexed 
using external characteristics. 

Size_andJife_Slag£ Distribution of Ha»e^dJjreenJjjrtles 

Two data sets were analyzed to identify the life stage of green turtles impacted in 
the fishery. One data set is from the harvested animals landed at Puerto Cabezas during 
the preliminary study between May 1992 and March 1993. Only female carapace lengths 
recorded during the preliminary study were compared to nesting females at Tortuguero, 
Costa Rica. Data from the preliminary study were used because the data collectors ability 
to accurately sex animals based on external characteristics was found to be highly reliable 
(see Results on Sex ratio of harvested green turtles). The second data set is from the 
harvested animals measured and sexed between February 1994 and December 1996 at 
eight data collection sites where turtles were landed. 

Using the preliminary data set, minimum straight carapace lengths (SLN) of 
harvested female green turtles landed at Puerto Cabezas, Nicaragua were compared to the 
maximum straight carapace lengths (SLT) of reproductively mature females measured on 



75 
the nesting beach at Tortuguero, Costa Rica (Caribbean Conservation Corporation unpubl 

data). Predicted SLN measurements were calculated from measured SLT of Tortuguero 

turtles. A regression equation to predict SLN was calculated from carapace lengths of 

animals I measured in Puerto Cabezas (see Methods on Turtle Morphometries). 

Using data collected at eight sites, the number of harvested male and female green 

turtles that were reproductively immature and mature were estimated for the RAAN and 

RAAS because smaller animals cannot be reliably sexed based on external characteristics 

(see Results on Sex ratio of harvested green turtles). For males, reproductive maturity 

was based on the presence of sperm, although this does not indicate that animals have 

reproduced (see Chapter 4). For females, reproductive maturity was based on the 

presence of corpora lutea in the ovaries (see Chapter 4) and the minimum size of females 

at the Tortuguero, Costa Rica rookery. Minimum plastron lengths of "mature" males and 

females were used as a cut-off between mature and immature animals. Estimates for the 

number of harvested males and females of reproductively immature and mature status 

were calculated by multiplying the number of harvested animals that were below and 

above the cut-off sizes for each sex by the proportion of harvested animals of each sex 

calculated for each region (see Results on Sex ratio of harvested green turtles). 

Statistical Analysis 
S^asxmal^ndJsmrxiralJiarvesLtrends 

Pearson correlation coefficient was used to determine if there was a relationship 
between the monthly number of green turtles harvested in the RAAN and monthly 



76 
rainfall recorded at Puerto Cabezas. Daily rainfall was recorded by either an assistant or 



me. 



Analysis of variance was used to compare the RAAN mean monthly harvest rate 
of green turtles during this study with the mean monthly harvest rate calculated by 
Montenegro Jimenez (1992) from 1985 to 1990. Although data from Montenegro 
Jimenez (1992) were collected from landings of turtles only at Puerto Cabezas, her data 
represent the total harvest of animals in the RAAN at that time because fishing activities 
were restricted during the Nicaragua civil-war. For the RAAS, time series analysis was 
used to examine the trend in the monthly harvest of green turtles. Time series analysis 
also was used to examine the trend in the monthly recorded harvest of hawksbills and 
capture of loggerheads for all data collection sites combined. Trend data were examined 
for the possibility of autocorrelated residuals. A regression model with autoregressive 
errors was used when autocorrelation among error terms was significant at P < 0.05; 
however, when they were not, a simple linear regression model was used. 
Turtle morphometries 

Pearson correlation coefficient was used to determine the relationship between 
body measurements and carapace length. Analysis of covariance was used to determine 
if males and females differed in their relationship between CLN and other body 
measurements. Dependent variables were log transformed when the assumptions of 
regression analysis were not met. Regression equations are reported separately when 
intercepts and slopes were significantly different between males and females, otherwise 
data were pooled and regression equations were recalculated. 



77 
Evaluating sex ratios 

McNemar's test of dependent samples was used to analyze the accuracy of the 
Puerto Cabezas data collector to determine sex of animals based on external 
characteristics (Zar 1996). A Chi-square test was used to determine if the sex ratio of 
harvested green turtles in the RAAN and RAAS differed. A normal approximation to a 
binomial distribution (One-sample Proportion test) was used to determine if the sex ratio 
of harvested animals differed from a one-to-one ratio. 

All statistical analyses were conducted using SAS software (SAS Institute, Inc. 
1989). Univariate procedures were used to determine if distributions approximate 
normality and a t-test was used to test for equality of variances. When assumptions for 
parametric analyses were not met, non-parametric tests were used. Means ± 1 S.D. are 
presented. 

Results 

Green Turtles 
Harvest levels 

From 1991 to 1993, the estimated annual harvest ranged from 6,169 to 9,440 
green turtles based on extrapolations of data collected at three or four sites, depending on 
the year (Figure 3.1). From 1994 to 1995, the estimated annual harvest ranged between 
9,413 to 1 1,077 green turtles based on extrapolations of data collected at eight collection 
sites. In 1996, the minimum annual harvest was 10,166 green turtles based on 



78 




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79 
data recorded at the same eight sites (Figure 3.1). Detailed harvest levels for each 
community are compiled in Appendix C. 
Seasonal and temporaL trends of ha rvest levels 

Mean monthly rainfall from April 1994 to May 1995 was 221.6 mm ±176.1 
(range = 13.7 - 547.0 mm, n = 14). There was no correlation between monthly rainfall 
recorded in Puerto Cabezas and the number of green turtles harvested in the RAAN (P = 
0.87, r = - 0.05). 

In the RAAN, from 1985 to 1990 (during the Sandinista/Contra war), 16,700 
green turtles (x = 245.6 turtles/mo ± 18.8, range = 0-739 turtles/mo, n = 68) were 
reported harvested (Montenegro Jimenez 1992). From February 1994 to January 1995 
and from December 1995 to April 1997 (post Sandinista/Contra war), 14,017 green 
turtles (x = 483.3 turtles/mo ± 142.7, range = 131 - 745 turtles/mo, n = 29) were 
harvested in the RAAN (Figure 3.2). There was a significant increase in the number of 
green turtles harvested/mo from the Sandinista/Contra war to the post-war period 
(ANOVA, F, 95 = 49.98, P < 0.0001). 

In the RAAS, from August 1994 to December 1996, 10,019 green turtles (x = 
345.5 turtles/mo ±171.8, range = 47 - 71 8 turtles/mo, n - 29) were harvested by four 
communities. Although the harvest rate has not changed significantly (P = 0.29, based on 
a regression model of autoregressive errors) there has been an increase of 58.7 turtles/yr 
during this 2.5-yr period (Y = 269.2 + 4.9X, where X is the number of months elapsed; 
Figure 3.3). Data for one RAAS community, Sandy Bay Sirpi, were available for a six-yr 
period which allowed the evaluation of harvest trends for a longer time period. From 



80 



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82 
January 1991 to December 1996 (72-mo period), 5,036 green turtles (x = 85.4 turtles/mo 

± 52.3, range = 3 - 237 turtles/mo, n = 59) were harvested. Based on a simple regression 
model the harvest rate of green turtles by Sandy Bay Sirpi turtlers has remained 
essentially constant at a decrease of 1.1 turtles/yr (P = 0.78) during this 6-yr period 
(Figure 3.4). 
Morphomelric parameters^ harvested turtles 

A total of 634 turtles were measured. For animals where sex was confirmed by 
dissection, minimum (notch-to-notch) curved carapace lengths (CLN) for females ranged 
from 75.0 - 1 13.2 cm (n = 276) and for males it ranged from 72.2 - 108.6 cm CLN (n = 
282). Pearson correlation coefficients are high (r > 0.89) among the various carapace 
lengths (i.e., CLN, minimum straight carapace (SLN), maximum curved carapace (CLT), 
maximum straight carapace (SLT)); plastron (PL); and body mass (WT) for sexes 
combined or separate. Correlation coefficients for each of plastron-to-vent length 
(VENT), tail length (TAIL), and mean claw basal area (xCBASE); regressed with each of 
CLN, SLN, CLT, SLT, PL, and WT are higher when sexes are separated (r > 0.69) than 
when sexes are combined (r < 0.52). Mean claw length (xCLEN) is more highly 
correlated with all but one (PL, r = 0.66) of the other eight body measurements for males 
(r > 0.73) than for females (r < 0.67). Between 23% and 55% more of the variation in 
xCLEN of males than females can be attributed to other body measurements. 
Coefficients are high among measurements of sexually dimorphic external characters 
(xCBASE:VENT or TAIL) for males and sexes combined (r > 0.92) and lower for 
females (r = between 0.72 and 0.76). Plastron and VENT are highly correlated with 



83 



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84 
TAIL for sexes combined or separate (r > 0.97). Correlation coefficients for all ten body 

measurements are shown in Appendix D. 

There was no significant difference between males and females for the 
relationship between CLN and each of SLT, log PL, and log WT; therefore, data were 
pooled. There was, however, a significant difference between males and females for the 
relationship between CLN and each of CLT, SLN, log VENT, log TAIL, log xCBASE, 
and log xCLEN; therefore, regression equations were calculated separately by sex. 
Although analysis of covariance showed a significant difference between males and 
females for CLN: CLT and CLN: SLN, there is no apparent sexual dimorphism as 
indicated by the very high coefficients for the sexes combined and separate (r = 0.99 for 
both). Regression equations and statistical results are summarized in Appendix E. 

Scatter plots of the 10 body measurements (each plotted against the other for a 
total of 45 pairs) were visually evaluated to determine if any pairs of measurements 
provide a means to distinguish between males and females. For 24 of the 45 pairs of 
measurements, divergence between males and females is obvious. However, not all pairs 
were equally divergent, nor was there complete divergence between males and females 
for any pair, particularly among the smaller sizes of animals. The greatest divergence 
between the sexes was observed in the plot of TAIL: WT, although TAIL plotted with 
CLN, SLN, CLT, SLT, PL (body lengths) were also highly divergent. Using the plot of 
TAIL.WT measurements, I developed a key to distinguish between males and females 
(Table 3.1). Although TAIL and WT were more easily distinguished on the scatterplot 



85 

Table 3.1. Keys to distinguish between male and female green turtles, Chelonia mydas, 
using tail length with either body mass or minimum curved carapace length 
(CLN). Scatterplots of tail length with body mass, and tail length with 
carapace length were used to distinguish between the sexes. For some 
measurements, however, sexes were indistinguishable (IND). Keys are based 
on confirmed males (n = 278) and females (n = 275). Cut-off measurements 
to distinguish between the sexes are approximate. Tail length = distance from 
posterior termination of the plastron midline to the tip of the straightened tail. 
CLN = distance along the midline from the anterior edge of the nuchal scute 
to the posterior termination of the midline. All animals measured were landed 
at Puerto Cabezas, Nicaragua between November 1993 and January 1995. 



Tail 

Length 

(cm) 




Body Mass (kg) 


Carapace Length (cm) 


dV 


?? 


IND 


dW 


?? 


IND 


<13 




>41 


<41 




>74 


<74 


13-15 




>60 


<60 


<75 


>87 


75-87 


15-17 


<46 


>64 


46-64 


<78 


>87 


78-87 


17-19 


<54 


>72 


54-72 


<81 


>88 


81-88 


19-21 


<58 


>80 


58-80 


<83 


>93 


83-93 


21-23 


<72 


>86 


72-86 


<88 


>93 


88-93 


23-25 


<86 


> 102 


86-102 


<94 


> 100 


94-100 


25-27 


<80 


>98 


80-98 


<94 


>99 


94-99 


27-29 


<92 


> 100 


92-100 


<93 


>96 


93-96 


29-31 


<90 


>90 




<96 


>96 




31-33 


<90 


>90 




<97 


>97 




33-35 


< no 


> 110 




< 100 


> 100 




35-37 


< 110 


> 110 




< 100 


> 100 




>37 


all 
males 






all 
males 







86 
between the sexes, I also developed a key based on TAIL:CLN because it is it is often 
difficult to weigh animals in the field (Table 3.1). 
Sex ratio of harvested turtles 

Between March 1994 and February 1995, the sex of 94.6% of 570 animals (size 
range = 72.2 - 1 13.2 cm minimum curve carapace length, CLN) were correctly identified 
by the Puerto Cabezas data collector using external characteristics. There was no 
difference in the misidentification of males or females (McNemar's test, % 2 = 0.29, df = 1, 
P > 0. 10). In addition, I recorded whether or not the development of male external sex 
characteristics (i.e., the length of the tail and the size and shape of the anterior flipper 
claws) was obvious for 51 1 animals ranging in plastron (PL) length from 55.2 to 90.2 cm 
(CLN range = 72.2 - 1 13.2 cm). Based on the percent of animals, grouped by 2.5-cm size 
classes, with obvious external sex characteristics and the percent error of the data 
collector, I decided that the accuracy of sexing animals with a PL length > 70.0 cm, based 
on external sex characteristics, was acceptable (Table 3.2). 

For turtles with PL lengths > 70.0 cm, there was a significant difference between 
the sex ratio of turtles harvested in the RAAN and RAAS (Chi-square test, y} = 59.1, df = 
1, P < 0.001). In the RAAN, the sex ratio of males to females was 1:1.7 which differs 
significantly from a 1:1 ratio (One-sample Proportion test, Z - 12.7, P < 0.0001). In the 
RAAS, the sex ratio of males to females was 1:1.1 which also differs significantly from a 
1:1 ratio (One-sample Proportion test, Z = 3.1, P < 0.001), however, this is probably not 



87 

Table 3.2. Accuracy of sex identification based on external characteristics with 
confirmation based on gonadal examination of harvested green turtles, 
Chelonia mydas, landed at Puerto Cabezas, Nicaragua from November 1 993 
to January 1995. The bold line at 70.0 cm is the minimum plastron length at 
which the sex of animals based on external characteristics was deemed 
acceptable. External characteristics are: the length of the tail in relation to the 
size of the animal and the size and shape of the anterior flipper claws. 



Plastron 

Length 

(cm) 


Sex Identification 

Based on External 

Characteristics 


Number of Animals 
with Obvious External 
Sex Characteristics (%) 


External Sex 

Identification 

Confirmed Based 

on Gonads 


Percent 
Error 


Female 


Male 


Yes 


No 


Female 


Male 


55.0-57.4 


1 


1 


0(0) 


2(100) 





2 


50.0 


57.5-59.9 


2 


1 


0(0) 


3 (100) 





3 


66.7 


60.0-62.4 


7 


7 


3(21.4) 


11 (78.6) 


6 


8 


7.1 


62.5-64.9 


24 


12 


12(33.3) 


24 (66.7) 


21 


15 


8.3 


65.0-67.4 


19 


24 


27 (62.8) 


16(37.2) 


19 


24 





67.5-69.9 


35 


42 


60 (77.9) 


17(22.1) 


38 


39 


3.9 


70.0-72.4 


33 


63 


90 (93.8) 


6 (6.3) 


36 


60 


3.1 


72.5-74.9 


28 


54 


80 (97.6) 


2 (2.4) 


28 


54 





75.0-77.4 


44 


30 


72 (97.3) 


2 (2.7) 


45 


29 


1.4 


77.5-79.9 


31 


17 


48 (100) 


0(0) 


31 


17 





80.0-82.4 


8 


4 


12(100) 


0(0) 


8 


4 





82.5-84.9 


16 





16(100) 


0(0) 


16 








85.0-87.4 


4 





4(100) 


0(0) 


4 








87.5-89.9 


3 





3 (100) 


0(0) 


3 








90.0-92.4 


1 





1 (100) 


0(0) 


1 








Totals 


256 


255 


428 (83.8) 


83 (16.2) 


256 


255 


2.7 



88 
biologically significant. The odds of capturing a female ^ 70.0 cm PL length in the 

RAAN are 1 .6 times greater than capturing a female in the RAAS. 

S ize and stag e distribution of h arvested tur tles 

There was a significant difference in the size of green turtles harvested in the 
RAAN and RAAS (Wilcoxon Rank Sums, Z - 34.6, P < 0.0001). In the RAAN, mean 
PL length was 69.7 cm ± 6.8 (range = 38.0 - 96.4 cm, n = 7,209) and in the RAAS, it was 
63.3 cm ± 1 1 .5 (range - 24.4 - 95.4 cm, n = 8,613; Figure 3.5). 

The size of females harvested in Nicaragua was compared to the size of nesting 
females at Tortuguero, Costa Rica to identify the life history stage of females harvested in 
the fishery. From April 1992 to March 1993, mean minimum straight carapace length 
(SLN) of females harvested in Nicaragua was 83.2 cm ± 7.5 (range - 64.2 - 1 13.8 cm, n = 
899) and the mode was the interval 77.0 cm to 79.9 cm (Figure 3.6). In 1988, mean 
predicted carapace length (SLN) of nesting Tortuguero females was 98.2 cm ± 4.2 (range 
= 88.3 - 1 12.9 cm, n - 120). Although carapace measurements taken for the two studies 
differed, the Pearson correlation coefficient between them was high (r = 0.99, P < 
0.0001). Therefore, I predicted SLN from straight maximum carapace length (SLT) 
measurements for Tortuguero females based on the equation SLN = -1.358 + 1 .002(SLT). 
There was a significant difference in mean carapace length (SLN) of harvested Nicaragua 
female green turtles and the mean predicted SLN of nesting Tortuguero females 
(Wilcoxon Rank Sums, Z = 15.6, P < 0.0001 ; Figure 3.6). Between May 1992 and March 
1993, 78.2% of the females landed at Puerto Cabezas were smaller than the smallest 
nesting female at Tortuguero in 1988. 



89 




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91 
Between February 1994 and December 1996, 54.2% of the harvested green turtles 

measured (n = 15,822 animals) were smaller than the smallest reproductively mature 
male (SRM; 13.3%) and female (SRF; 40.9%), based on the presence of sperm for males 
and corpora lutea for females. In the RAAN, of the animals measured, an estimated 
4,556 (63.2%) were females, of these 64.9% (2,957) were smaller than the SRF. In 
contrast, of the estimated 2,653 (36.8%) males, 14.2% (377) were smaller than the SRM. 
In the RAAS, an estimated 4,530 (52.5%) were females, of these 77.7% (3,518) were 
smaller than the SRF and for the estimated 4,083 (47.4%) males, 42.3% (1,729) were 
smaller than the SRM. 
Irend^in size distribution of harv ested an imals 

Using a regression analysis, mean plastron length (PL) of harvested animals in the 
RAAN has increased 2.4 cm from February 1994 to April 1997 (r = 0.10, P < 0.0001; 
Table 3.3). When measurement data from each site were analyzed separately, however, 
the change in mean PL of harvested animals for three of the four sites (Puerto Cabezas, 
Awastara, and Sandy Bay) is < 0.5 cm for the time period (P ^ 0.12 for the three sites). 
At the fourth site (Dakra) there was a 3.5 cm increase in mean PL. However, for animals 
measured at the commercial center of Puerto Cabezas, where animals captured by turtlers 
from the three communities, Awastara, Dakra, and Sandy Bay are landed, there was an 
increase of 0.3 cm in mean PL (P = 0.27; Table 3.3). 

In the RAAS, mean plastron length of harvested animals decreased 4.6 cm from 
July 1994 to December 1996 (r = - 0.09, P < 0.0001). At three of the four sites, mean 
plastron length of harvested animals decreased from 0.3 cm to 8.2 cm during the time 



92 

period (Table 3.3). At only one site, Sandy Bay Sirpi, mean plastron length increased 2.7 
cm during the time period. 



Table 3.3. Simple regression analysis of the change in mean plastron length over time of 
harvested green turtles, Chelonia mydas, from offshore waters of Caribbean 
Nicaragua. Animals were measured when they were landed at the turtler's 
community or at the commercial center of Puerto Cabezas. Data were 
analyzed for each data collection site and by region. RAAN = Region 
Autonoma del Atlantico Norte) and RAAS = Region Autonoma del Atlantico 
Sur). 



Site or Data Collection Periods Change in Mean Size 

Region (Length of Period) for the Time Period n r P-value 



RAAN sites 
combined 

Awastara 



Dakra 



Sandy Bay 



Feb 94 - Apr 97 
(1,184 days) 

Feb 94 - Jan 95; 

Dec 95 - Apr 97 

(881 days) 

Feb 94 - Jan 95; 

Dec 95 - Apr 97 

(881 days) 

Feb 94 - Feb 95; 

Dec 95 - Apr 97 

(909 days) 



+ 2.4 cm 



0.08 cm 



+ 3.5 cm 



+ 0.5 cm 



8,807 
1,491 

1,341 

2,088 



0.10 



0.0 



0.17 



0.03 



< 0.0001 



0.85 



< 0.0001 



0.12 



Puerto 
Cabezas 


Feb 95 - Apr 97 
(819 days) 


+ 0.3 cm 


3,886 


0.017 


0.27 


RAAS sites 
combined 


Jul 94 - Dec 96 
(914 days) 


- 4.6 cm 


8,371 


-0.09 


< 0.0001 


Rio Grande 
Bar 


Jul 94 - Dec 96 
(914 days) 


- 0.3 cm 


1,426 


-0.01 


0.77 


Sandy Bay 
Sirpi 


Jul 94 - Dec 96 
(914 days) 


+ 2.7 cm 


2,167 


0.10 


< 0.0001 


Tasbapaune 


Jan 95 - Dec 96 
(730 days) 


- 5.1 cm 


4,371 


-0.1 


< 0.0001 


Set Net 


Jul 94 - Dec 96 
(914 days) 


- 8.2 cm 


407 


-0.2 


< 0.0001 



93 
ther back Turtles 

Harvest levels 

For hawksbills, the minimum harvest in 1994 was 86 animals. In 1995, the 
minimum harvest was 109 animals and in 1996, it was 53 animals. For loggerheads, the 
estimated capture in 1994 was 173 animals. In 1995, the minimum number of animals 
captured was 169, and in 1996, it was 483 animals. From 1994 to 1996, only four 
leatherbacks, all in 1995, have been reported captured. Three of them were captured by 
turtlers of Dakra (RAAN) and one by turtlers of Tasbapaune (RAAS). Detailed annual 
harvest levels for each data collection site by species are located in Appendix F. 
Temporal trends in the ha rve st of h aw ksbill and c apture of loggerhead turtles 

For the Caribbean coast of Nicaragua, the mean monthly harvest rate of 
hawksbills from December 1993 to December 1996 was 6.9 ±3.9 animals (range = 1 - 
18, n = 37). Based on a simple regression model, the harvest rate of hawksbill turtles has 
remained essentially constant during this 3-yr period (r = -0.23, P = 0.17, Y = 8.44 - 
0.083(ME), where ME is the number of months elapsed; Figure 3.7A). 

For loggerheads, the mean monthly capture rate from September 1994 to 
December 1996 was 25.3 ± 17.1 animals (range = 3 - 63, n = 28). Based on a simple 
regression model the capture rate of loggerheads has increased significantly at 17 
turtles/yr during this 2.25-yr period (r = 0.68, P < 0.0001, Y = 4.80 + 1.42(ME), where 
ME is the number of months elapsed; Figure 3.7B). 



94 



W 
H 



A) Hawksbills 

NT = 8.44 - 0.083(ME) 
P = 0.17, r = -0.23 



70 

60 
50 
40 
30 
20 
10 


1993 1994 1995 1996 



..." = » M«'' 



* •• 



• ■•* _• 



70 
60 
50 
40 
30 
20 
10 




B) Loggerheads 

NT = 4.80+1.42(ME) 
P < 0.0001, r = 0.68 



• • 



1994 1995 1996 



p* 



Figure 3.7. Number of A) hawksbill, Eretmochelys imbricata, and B) loggerhead, 
Caretta caretta, turtles reported captured from the Caribbean waters of 
Nicaragua. Hawksbills are reported from December 1993 to December 1996 
(37 mo) and loggerheads from September 1994 to December 1996 (28 mo). 
NT = number of turtles, ME = months elapsed. 



95 
Morphometric parameters of har vested haw kshill turtles 

Ten body measurements were recorded for six hawksbills. Mean female 
minimum curved carapace length (CLN) was 77.8 cm ± 7.4 (range = 67.0 - 85.6, n - 5) 
and the CLN of the male was 73.7 cm. Simple statistics for the ten body measurements 
are summarized in Appendix G. Because loggerheads are not landed at Puerto Cabezas 
none were measured. 
Demographic parameters^of harvestedJiawksbills 

From December 1993 to December 1996, the sex ratio of harvested hawksbills 
was 1M : 2F (n = 42 animals) for animals with plastrons > 55.9 cm (for animals where 
sex was determined by external characteristics) or when sex was confirmed during 
butchering. Sex ratios of harvested animals for the RAAN (n = 24 animals) and RAAS (n 
= 18 animals) were the same. Because hawksbills are not sexually dimorphic until they 
approach adult size, a minimum plastron length was used to identify which animals could 
be accurately sexed based on external characteristics. This cut-off measurement is based 
on the minimum size (55.9 cm plastron) reported for nesting hawksbills at Tortuguero, 
Costa Rica (Carr et al. 1966; Bjorndal et al. 1985). Although plastron measurements 
taken in Nicaragua (curved) and in Costa Rica (straight) were not identical, the difference 
in these two measurements is probably less than a few centimeters based on plastron 
length measurements taken from green turtles (C. Campbell unpubl. data). 

There was a significant difference in mean plastron length of hawksbill turtles 
harvested in the RAAN and RAAS (ANOVA, F liM = 10.29, P = 0.0019). In the RAAN, 
between December 1993 and December 1996, mean plastron length was 63.3 cm ± 0.1 



96 
(range = 32.0 - 80.7, n = 59; Figure 3.8). In the RAAS, between January 1995 and 
December 1996, mean plastron length was 55.7 cm ± 1 1.8 (range = 14.0 - 75.4, n = 31; 
Figure 3.8). 

Overall, regardless of sex, 71.1% of the harvested hawksbills measured (n = 64 
animals) were larger than the smallest nesting female (SNF) at Tortuguero, Costa Rica. 
In the RAAN, 78.0% (46) were larger than the SNF. In contrast, only 58.1% (18) were 
larger than the SNF in the RAAS. 
Demog raphic paramete r s of captured l oggerheads 

Loggerheads are discarded, unconscious or dead, where they are captured, or used 
for lobster trap or shark bait. Thus, the data collectors had the opportunity to measure 
only 16 loggerheads. All loggerhead measurements are from the RAAS. Mean plastron 
length was 62.5 cm ± 10.5 (range = 47.3 - 84.3). 

Discussion 

Green Turtles 

CiirjtejiLandJiisJMicalJian^^ irends 

For the past six years, the estimated total annual harvest of green turtles from the 
Nicaragua foraging ground ranged between 6,000 and 1 1,000 animals. Estimated annual 
harvests are minimum levels, however, because harvest levels for 1991 to 1993 were 
based on data collected from 50.0% to 62.5% (4 to 5 sites) fewer sites than during the 
1994 to 1996 period. In addition, estimated yearly harvests do not include turtles 
harvested by three additional turtling communities in the RAAN, or harvests by the Rama 



97 




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98 
Indians in the RAAS. Also, an unknown number of marine turtles are captured 
incidentally to other fishing activities that occur off Nicaragua's coast, i.e., shrimp 
trawling, lobster diving, and hook and line fisheries. 

In the Region Autonoma del Atlantico Norte (RAAN), the monthly harvest of 
green turtles for 29 mo between February 1994 and April 1997 has almost doubled since 
the six-yr period from 1985-1990. The lower harvest rate of green turtles during the 
1980s probably resulted from the civil unrest and military conflicts created by the 
Sandinista/Contra war. According to local informants, many coastal communities were 
abandoned during the war. In the RAAN, the Sandinista military only allowed fishing 
trips when they originated from Puerto Cabezas. During times of heightened military 
activity offshore fishing was either too dangerous or not allowed at all. These factors 
probably decreased harvest levels of marine turtles as well as terrestrial and other aquatic 
resources. 

Harvest rates of marine turtles during the 1980s (Sandinista/Contra war period) 
are not available for the Region Autonoma del Atlantico Sur (RAAS). For a post-war 
period (August 1994 to December 1996), however, monthly harvest rates of green turtles 
in the RAAS have remained relatively constant. Although monthly harvest rates for the 
RAAS are available for a relatively short time period, the conclusion that harvest rates 
have remained stable is also supported by the relatively constant monthly harvest of green 
turtles by one RAAS community, Sandy Bay Sirpi, for a 6-yr period (1991-1996). Thus, 
although harvest rates are highly variable (see Figure 3.3), the results suggest that the 



99 



overall harvest trend in the RAAS during the 1990s has, thus far, remained relatively 
unchanged. 

Knowledge of historical harvest levels and patterns are important to assessing the 
possible status of the population and the potential impact of current harvest levels. 
Unfortunately, no information is available on harvest rates prior to European arrival. As 
early as 1633, the English established a trading station at Cabo Gracias a Dios, near the 
Honduras/Nicaragua border. By 1722, Jamaican and possibly Cayman boats were 
annually visiting the Miskito Cays of Nicaragua to catch and purchase green turtles and 
hawksbill shell from the Miskitu Indians (Fernandez cited in Parsons 1962) and by the 
early 1800s, Cayman Islanders were regularly turtling off the coast of Nicaragua (Lewis 
1940; Parsons 1962). Simmonds (cited in Parsons 1962) reported that by 1878, up to 
15,000 turtles annually were landed in Europe, most of them having been caught by the 
Cayman fleet turtling in Nicaraguan waters. During the first-half of the 20th century 
approximately 2,000 to 4,000 green turtles were harvested annually from the Nicaraguan 
coast by Cayman boats (Ingle and Smith 1949; Parsons 1962). From 1958 to 1967, 1,000 
to 2,350 green turtles annually were exported from Nicaragua by Cayman boats 
(Nietschmann 1973). By the mid-1960s, the Nicaraguan government no longer permitted 
Cayman Islanders to turtle within their waters (Rainey and Pritchard 1972; Nietschmann 
1973, 1976). From 1966 to 1976, Nicaragua exported 445,500 kg (equivalent to 
approximately 10,000 animals) of sea turtle products into the United States alone during 
7 of these 10 years (Cato et al. 1978). In the late 1960s and early 1970s, three turtle 
processing plants began operations in Nicaragua (Nietschmann 1973, 1974). 



100 
Unfortunately, prior to the late 1 960s, estimates of the harvest were based only on export 

levels and did not include the harvest of animals for local consumption. 

The current annual harvest of approximately 10,000 to 1 1,000 green turtles is 
similar to or exceeds annual exploitation levels reported for the first-half of the 1970s 
(Nietschmann 1973, 1979a, b), when evidence suggesting declines in foraging and 
nesting populations were attributed by the scientific community to overexploitation (Carr 
1969; Nietschmann 1972, 1973, 1974, 1976; Weiss 1976). From 1969 to 1976, during 
the operation of three turtle processing plants in Nicaragua, there were an estimated 6,000 
to 10,000 green turtles harvested annually for exportation and local consumption 
(Nietschmann 1973, 1979a, b; Bacon 1975). Indications that the foraging ground 
population was in decline were based on: 1) a decrease in capture rates (in 1971 it took 
an average two person-days to capture one turtle, and by 1975 it took an average six 
person-days to capture one turtle, Nietschmann 1973, 1979a; Weiss 1976) , 2) a decrease 
in the capture of larger turtles (Nietschmann 1972, 1973, 1976), and 3) a severe decline in 
the 1974 nesting density of females at the Tortuguero, Costa Rica rookery (Carr pers. 
com. to Nietschmann 1976), the source of most adult turtles on the Nicaragua foraging 
ground (Carr et al. 1978; Bass et al. in press). 

Additional indications that current harvest levels are as high or higher than those 
in the recent past is demonstrated by comparing past and present harvest levels for two 
RAAS communities. In Tasbapaune, there has been a two- to three-fold increase in the 
harvest of green turtles compared to 25 years ago, just prior to the operation of the turtle 
processing plants. Nietschmann (1972, 1973) reported that 819 turtles were harvested 



101 
during a 12-month period beginning in 1968 compared to a range of 1,684 to 2,536 turtles 
harvested/yr from 1994 to 1996. During the operations of the processing plants, Weiss 
(1976) reports the harvest level for Sandy Bay Sirpi at 913 turtles during a 12-month 
period beginning in 1972. For five of the six years from 1991 to 1996, green turtle 
annual harvest rates ranged from 870 to 1,438, rates which are similar to or exceed the 
1972 rate. The early 1970s was a period that, until now, probably had the highest harvest 
levels to occur on this coast. 

The occurrence of several major events in Costa Rica and Nicaragua during the 
late 1970s and 1980s, probably resulted in a decrease in the harvest rate and aided in 
some level of recovery of the foraging population. In 1975, the Tortuguero National Park 
in Costa Rica was established, site of the largest green turtle rookery in the Caribbean, to 
protect breeding animals in nearshore waters and nesting females and their eggs. This is 
significant to the Nicaragua foraging population because 1) based on tag recoveries of 
nesting females from Tortuguero the majority use the Nicaragua foraging grounds (Carr 
et al. 1978) and 2) based on mitochondrial DNA analysis the majority of subadult and 
adult animals foraging in Nicaragua are from the Tortuguero rookery (Bass et al. in 
press). By 1973, the processing plant in Puerto Cabezas was closed, and by 1977, the 
other two plants in Nicaragua were closed (Nietschmann 1976, 1979b) and Nicaragua 
became a signatory to the Convention on International Trade in Endangered Species of 
Wild Fauna and Flora, CITES (Hemley 1994). During the 1980s, the country was 
involved in a 10-yr long civil war that displaced many people from their Caribbean 



102 
lowland communities and greatly reduced the exploitation of terrestrial and aquatic 
resources (Nietschmann 1995). 

These events would certainly have reduced the harvest of marine turtles from the 
high levels of the late 1960s and early 1970s, providing approximately 15 yrs for the 
segment of the population targeted in the fishery to increase and could explain why green 
turtle harvest levels are as high as they are today. During the war years of 1985 to 1988, 
between 1,600 and 3,000 green turtles were annually landed at Puerto Cabezas, which 
was the total harvest in the RAAN at the time (Montenegro Jimenez 1992). For 1989 and 
1990, when people began to return to their homes and life began to return to some degree 
of normalcy, 3,200 and 3,380 green turtles, respectively, were landed at Puerto Cabezas, 
again the total harvest in the RAAN (Montenegro Jimenez 1992). In comparison, 
between 1994 and 1996, 5,000 to 6,000 green turtles were harvested annually in the 
RAAN. 

Although a law by the central government to protect green turtles has been 
established, it is ineffective and no cultural taboos or restrictions currently exist within 
the Miskitu society to protect against overharvesting the resource (V. Renales pers. com.). 
At present, only inclement weather and holidays limit the Miskitu Indian marine turtle 
harvest. These limitations do not occur often enough or for sufficient periods of time to 
diminish overall harvest levels. Almost all monthly harvest totals remain high suggesting 
that during each month there are a sufficient number of good weather days and few 
enough holidays to maintain a fairly constant harvest rate. In contrast, Nietschmann 
(1973) reported that prior to the opening of the turtle processing plants turtlers divided 



103 
their time among hunting, turtling, and tending to agricultural plots depending on the 

season, other household or community demands, and availability of turtles on the 
foraging ground. For one community, a decrease in monthly turtle harvest levels 
occurred between April and July and again between September and November 
(Nietschmann 1973). These declines in harvest levels were attributed to an increase in 
rainfall exacerbated in the spring months by the temporary emigration of breeding adult 
turtles from the foraging grounds (Nietschmann 1973). However, when the turtle 
processing plants opened and the demand for green turtles increased, turtlers extended 
their turtling activities year around (Nietschmann 1 973). In the present study, a decline in 
the harvest rate did not occur during the months turtles migrate to the nesting beach 
probably because the majority of animals harvested are subadults and have not yet begun 
to make seasonal migrations to the nesting beach. 

Current local and regional demands for green turtle meat within Nicaragua have 
grown to equal or exceed export demands for sea turtle products that occurred during the 
early 1970s. There are also indications that the regional demand for green turtle meat in 
Nicaragua has not yet been satiated. According to D. Castro (pers. com.), Miskitu 
Indians from the Rio Coco region (located on the border of Honduras) and from the 
interior areas, who prior to the Sandinista/Contra war did not eat sea turtle meat, have 
settled in Puerto Cabezas and are now consuming it. In addition, D. Castro (pers. com.) 
reports that animals are transported by truck from Puerto Cabezas to the Rio Coco region 
where more people are becoming accustomed to eating sea turtle meat, thus, creating a 
demand where none previously existed. 



104 
Demography of the harvest 

For three data subsets and two different time periods, the majority (78.2% for 
Puerto Cabezas, 64.9% for the RAAN, and 77.7% for the RAAS) of harvested females 
were smaller than the smallest nesting female at Tortuguero indicating that most of the 
harvested females were immature. For males, the majority (85.8% for the RAAN and 
57.6% for the RAAS) of harvested animals were larger than the smallest male observed 
with sperm in the reproductive tract indicating that most of the harvested males are 
physiologically mature. The percent of immature animals of both sexes in the harvest is 
probably higher, however, because the cut-off measurements used to categorize maturity 
status for males and females were based on the smallest animals of each sex with 
observed evidence of reproductive maturity. However, not all animals will become 
sexually mature at the minimum body size (Carr and Goodman 1970; Limpus et al. 
1994a, b) nor will all animals breed once they have reached physiological maturity. 

When all harvested animals that were measured are considered, regardless of sex, 
mean plastron length (66.2 cm) is 13.6 cm and 14.6 cm smaller than the mean plastron 
length of nesting females at the Tortuguero rookery (Carr and Ogren 1960, x = 80.8 cm 
predicted plastron based on maximum carapace measurements; Bjorndal and Carr 1989, 
x = 79.8 cm plastron length). Although plastron measurements reported for Tortuguero 
animals are straight-line and for Nicaragua animals curved, the difference in these 
measurements is probably less than 2.0 cm (C. Campbell unpubl. data) and would not 
account for the approximately 14 cm difference in means reported between the foraging 
ground and nesting beach. 



105 
Previous studies conducted in Nicaragua provide data on the size and sex ratio of 
harvested animals with which to compare current demographic data of harvested animals. 
The sex ratios of animals harvested in the RAAN (1M:1.7F) and RAAS (1M:1.1F) for 
this study are the same as those observed by Mortimer (1981) in March 1975 and June 
1976 combined. Carr and Giovannoli (1957) however, report a sex ratio of 1M:2.6F for 
animals harvested from the Miskito Cay region (RAAN) between February and April 
1956. Assuming that the sex ratio of harvested animals is a reflection of the foraging 
population, these data suggest that the proportion of females in the foraging population in 
the RAAN decreased between 1956 and 1976. Since 1976, however, the sex ratio in both 
the north and south regions of the country have remained the same. The decrease in the 
proportion of females in the harvest since 1956 could reflect the increased susceptibility 
of females when on the nesting beach and subsequent increased mortality rates. At this 
time there is no reason to believe that entanglement nets are biased towards the capture of 
females, however, possible behavioral differences between the sexes, e.g., movement 
patterns and habitat use, could account for differences in net captures. 

The mean weight of animals harvested has, apparently, decreased during the past 
20 yrs. The mean live weight (80.6 kg ± 23.7, n = 1 ,438) for green turtles landed in 
Puerto Cabezas from April 1992 to March 1993 was less than the 90.7 kg mean live 
weight reported for green turtles harvested by Tasbapaune turtlers during a 12-month 
period beginning in 1968 (Nietschmann 1972, 1973). In addition, turtlers have reported 
decreasing the mesh size of their nets from a 46-cm bar to approximately 38 - 43-cm bar 
so that smaller turtles do not escape (V. Renales pers. com.; P. Julias pers. com.). This 



106 
suggests turtlers are no longer capturing a sufficient number of larger animals to meet 

their economic needs and demand for turtle meat. 
Trends in the length of cap tured animals 

During this study, for measurements from all turtling communities combined in 
the RAAN, there has been a significant increase in the length of harvested animals during 
the past 3.25 yrs. This apparent increase in length of harvested animals during the study 
period, however, is a result of the data from only one of the four data collection sites 
included in this analysis. The length of animals from three of the four sites increased < 
0.5 cm, while for Dakra, the length of harvested animals increased 3.5 cm. Because 
turtling communities in the RAAN overlap extensively in their use of capture locations 
(see Chapter 2), there is no reason to expect the mean length of harvested animals for one 
community to be different from the other three data collection sites. The apparent 
increase in the length of animals harvested by Dakra is probably due to errors in 
measuring or in data recording and, therefore, is probably incorrect. There probably has 
not been a change in the size of animals harvested in the RAAN during this 3.25-year 
period. 

In the RAAS, overall, there has been a significant decrease in the size of harvested 
animals during the past 2.5 yrs. The most northern turtling community in the RAAS, 
however, showed a significant increase in size, while the other three communities showed 
a decrease in the size of harvested animals. Interestingly, among the three communities 
that showed a decrease in plastron length, the magnitude of the decrease is larger, from a 
north to south direction on the turtling grounds. Because turtling communities in the 



107 
RAAS rarely overlap in their use of turtle capture locations (see Chapter 2), it is possible 
that different levels of harvest pressure in the recent past could have impacted areas of the 
foraging ground differently. We know nothing, however, about movement patterns and 
habitat use of turtles on this foraging ground. 

Hawksbill Turtles 

Historical and current Jiarve&tlevels 

Although in recent years the harvest rate of hawksbills from Nicaraguan waters 
has remained relatively constant (at 6.9 ±3.9 turtles/mo from December 1993 to 
December 1996), compared to earlier harvest rates there has been a 10-fold decline. For 
the late 1960s and early 1970s, Nietschmann (1981) estimated an annual harvest of 1,000 
to 1 ,200 hawksbills from Caribbean Nicaraguan waters. For one community, 
Tasbapaune, Nietschmann (1972, 1973) reported a harvest of 27 hawksbills from January 
to June in 1969 and approximately 107 hawksbills for the same six months in 1971. 
From January to June during this study, Tasbapaune residents harvested 35 hawksbills in 
1995, 5 hawksbills in 1996, and 2 hawksbills in 1997. On average, this represents a 
479% decrease in the harvest rate of hawksbills by Tasbapaune residents between the 
late- 1960s/early- 1970s and the mid-1990s. 

The decline in the harvest rate of hawksbills in Nicaragua is probably due to a 
decrease in the hawksbill population and not a decline in the demand for hawksbill scutes 
(the source of tortoiseshell). Worldwide, hawksbill populations are in decline due 
primarily for the demand in tortoiseshell and stuffed animals for the tourist trade (King 



108 
1982; Witzell 1983; Milliken and Tokunaga 1987; Bjorndal et al. 1993; Meylan 1997a). 
Hawksbills together with green turtles were important commodities in trade relationships 
developed between Nicaragua and the English and later the United States (Nietschmann 
1976). At one time, hawksbill shell was a leading export to Europe and the skin was 
exported to the United States (Nietschmann 1976). Although it has been illegal to export 
marine turtle products from Nicaragua since 1977, when it became a signatory of CITES 
(Hemley 1994), there is still a market for hawksbill scutes within Nicaragua. 

Tortoiseshell is purchased from fishers by local artisans who make it into various 
jewelry items. During the 1980s, there were approximately 30 artisans of tortoiseshell in 
Puerto Cabezas (J. Lackwood pers. com.). Since the departure from Nicaragua of citizens 
from Soviet-block countries, after the election of the pro-democratic presidency of 
Chamorro in 1990, the sale of tortoiseshell products in Puerto Cabezas has declined (J. 
Lackwood pers. com.). By 1992, there were only 17 artisans still working tortoiseshell in 
Puerto Cabezas (J. Lackwood pers. com.). However, the relatively easy preparation of 
hawskbill shell for sale or storage, combined with instability in the national economy, and 
fluctuations in the demand for hawksbill shell encourages people to continue the 
opportunistic harvest of hawksbills, even though current demand is low. Today, 
tortoiseshell jewelry is made in both cottage-based industries, as well as, in retail jewelry 
stores and can be readily found for sale throughout the country. In the Managua 
international airport, tortoiseshell jewelry is found for sale along with many other tourist 
items. At the Puerto Cabezas regional airport, local artisans daily display for sale their 



109 
tortoiseshell products. In Bluefields, a retail jewelry store sells locally manufactured 
hawksbill shell products. 
Demogra phy of th e hardest 

The sex ratio of harvested hawksbills is 1M : 2F in the RAAN and RAAS and 
both juvenile and adult animals are harvested (range = 14.0 - 80.7 cm plastron range). 
Regardless of sex, the majority (71.1 %) were larger than the smallest nesting female 
(55.9 cm) reported for the Tortuguero, Costa Rica rookery (Carr et al. 1966; Bjorndal et 
al. 1985). This does not imply, however, that all animals were reproductively mature. 
Like green turtles, not all hawksbills will become sexually mature at the minimum body 
size (Limpus 1992a). Although the majority of animals harvested in both the RAAN 
(78.0%) and RAAS (58.1%) are larger than the smallest nesting female at Tortuguero, the 
mean plastron length of animals harvested in the RAAN is significantly larger than in the 
RAAS. 

The harvest of hawksbills is probably less selective for a particular size class of 
animal than the harvest of green turtles because not only are hawksbills captured in nets 
set for green turtles, but also when encountered opportunistically by lobster divers on the 
reefs, or when they come ashore to nest (primarily in the RAAS). However, juvenile 
hawksbills are less well represented in the harvest than might be expected. This might be 
explained by some combination of the following factors: 1) the large mesh size of the 
nets selects against their capture; 2) some divers choose not to capture small animals; and 
3) there are fewer juveniles in the population because of low recruitment resulting from 
the overharvest of adults and eggs reported by Nietschmann (1981). Because small 



110 
juveniles are known to occur in this area (Nietschmann 1981; D. Castro pers. com.; 
Lagueux pers. obs.), the low representation of small animals in the harvest is most likely 
due primarily to fewer juvenile animals in the population. 

Lo ggerhead a nd LeatherhackJurtles 

During the past 2.25 yrs, an average of 25.3 loggerheads were captured/mo. The 
capture rate, however has increased significantly by an average of 17 turtles/yr for this 
same time period. Since loggerheads are not targeted in the fishery and have little or no 
economic value, this increase in harvest rate is likely a result of improved reporting by 
turtlers and data recording by local data collectors. Loggerhead meat has never been in 
demand for human consumption on the Nicaragua coast; however, over the years, 
loggerheads, as well as, greens and hawksbills have been harvested for their throat and 
shoulder skin (Nietschmann 1972, 1981 ; Bacon 1975) and more recently as bait for the 
shark and lobster trap fisheries. 

Although it is possible to release animals unharmed, most turtlers club them 
unconscious to facilitate their removal from the nets, prior to release. The use of 
entanglement nets allows captured animals to be released uninjured, however, the 
majority, if not all, of the loggerheads captured probably die because the animals are 
likely to drown when released unconscious. Because the majority of animals are 
discarded at sea, it is difficult to determine demographics of captured animals. The size 
range of the few loggerheads measured, however, suggests that both large juveniles and 
adults use Nicaragua's offshore waters (see Dodd 1988 for a review of loggerhead sizes). 



Ill 

The capture of leatherback turtles by this fishery does not appear to be a problem. 
Only four animals have been reported captured from 1 994 to 1 996, although this is 
probably a minimum level of human-induced mortality. Little is known about the size 
and sex of leatherbacks that use this habitat. However, turtlers reported that the four 
captured animals were "large", indicating they were possibly large juveniles or adults. In 
addition, infrequent nesting of leatherbacks has been reported near Rio Grande Bar and 
hatchlings were observed on the beach in March 1994 (L. Churnside pers. com.) 

The importance of the beach and offshore habitats to the survival of loggerhead 
and leatherback populations in the Caribbean is unknown, and the rookeries of these 
animals have not been identified. More studies will be needed before we can evaluate the 
effect of current fishery practices on either of these species. 

Conclusions 

This study is the first to quantify harvest levels and identify demographic 
characteristics of harvested turtles along most of the Caribbean coast of Nicaragua. 
Although only green turtles are targeted in the fishery, three additional species ~ 
hawksbills, loggerheads, and leatherbacks are also impacted by the fishery. Current 
harvest levels of green turtles are as high or higher than they have probably ever been on 
this coast. Although harvest levels of hawksbill turtles have declined since the early 
1970s, this probably reflects a decline in the population rather than in the demand for 
tortoiseshell. Prior to this study, no data were available on the capture and occasional use 
of loggerhead turtles in this fishery. Because loggerheads probably die as a result of 



112 
being released unconscious, populations in the region will likely be affected. Thus, it is 
necessary to determine their natal rookeries to monitor for population trends. It appears 
that leatherbacks are only rarely captured in the Miskitu Indian marine turtle fishery, and 
thus, their populations are probably not affected by this fishery. 

The majority of green turtles harvested in the fishery are large juvenile females. 
In contrast the majority of hawksbills harvested are adult females. Insufficient data are 
available to evaluate the size and sex of captured loggerheads and leatherbacks, although 
data on the few loggerheads measured and reports from turtlers on leatherbacks indicate 
large juveniles and adults of both species are captured. If harvest rates are higher than 
recruitment rates, resulting in declining populations, then clearly the harvest of females 
could further impede the ability of these populations to recover. Specific 
recommendations to manage the harvest are provided in Chapter 6. 

Marine turtles are highly migratory during several life stages. Therefore, 
monitoring harvest rates and demographic data of the Nicaragua fishery will aid in 
evaluating the impact of this fishery on marine turtle populations throughout the greater 
Caribbean. These data are also necessary to monitor changes in the turtle populations 
resulting from management strategies or changes in harvest patterns. 



CHAPTER 4 

REPRODUCTIVE CHARACTERISTICS AND CYCLICITY 

OF GREEN TURTLES ON A FORAGING GROUND 



Introduction 

For a species, reproductive success of individuals is critical to the persistence of 
that species through time. An understanding of an animal's reproductive biology is 
important to the conservation of the species and can be crucial to properly manage the 
recovery of threatened or endangered species. In coastal areas of the world, where 
subsistence or traditional use of sea turtles occurs, an improved understanding of turtle 
reproductive cycles can aid in developing strategies to reduce detrimental affects of 
exploitation. 

Studies on the reproductive biology of sea turtles have examined a variety of life 
stages and aspects of their reproductive cycle. The earliest, and to date, the majority of 
reproductive studies, have focused on the nesting female (Moorhouse 1933; Carr and 
Giovannoli 1957; Hendrickson 1958; Caldwell 1959; Carr and Ogren 1959, 1960; Carr 
and Hirth 1962; Carr et al. 1966; Bustard 1972). Studies of nesting females have focused 
on characterizing intra- and interseasonal reproductive effort by documenting clutch size, 
number of egg clutches laid per season, relationship between female size and clutch size, 
and internesting intervals (Pritchard 1969; Schulz 1975; Carr et al. 1978; Hirth 1980). 

113 



114 
More recent studies have focused on the endocrinology of nesting females by 
examining blood levels of gonadotropins and other hormones pre- and post- ovulation 
and during oviposition (Licht 1980; Licht et al. 1980, 1982, 1985; Wibbels 1988; Rostal 
et al. 1990; Guillette et al. 1991; Whittier et al. 1997). Blood samples are removed 
during different stages of the nesting process and hormone concentrations analyzed. A 
few studies have used laparoscopy as a non-lethal, albeit, invasive method to confirm an 
animal's sex and to determine reproductive status based on the macroscopic condition of 
the gonads or through histological examination of gonadal biopsies (Owens 1982; 
Limpus and Reed 1985a, b; Limpus 1992a; A. Meylan et al. 1992; P. Meylan et al. 1992; 
Meylan and Meylan 1994; Meylan et al. 1994). Advantages to laparoscopy are that the 
reproductive system can be evaluated directly, histology can be used to evaluate biopsies 
of gonadal tissue, animals are not sacrificed, and the same individual can be examined 
repetitively over time with apparently little or no negative effects (Limpus and Reed 
1985a; Meylan in lift.). A few studies have reported on morphometries or seasonal 
changes in the reproductive system of sea turtles (Aitken et al. 1976; Solomon and Baird 
1979; Owens 1980; Licht et al. 1985). However, no study has examined monthly 
changes throughout the course of a year. The worldwide endangered status of sea turtles 
prohibits their sacrifice for research. Thus, the study of the morphometries of the 
reproductive system is limited to examining dead animals opportunistically, killed 
incidentally in marine fisheries or by other human activities, or harvested for human use. 

The legal harvest of green turtles, Chelonia mydas, on the Caribbean coast of 
Nicaragua by Miskitu Indians for local use provides an excellent opportunity to examine 



115 
the reproductive cycle and to determine the reproductive status of harvested marine 
turtles from a foraging ground. Due to the large number of animals harvested (currently a 
minimum of 1 0,000 - 1 1 ,000 green turtles annually), there is almost an unlimited supply 
of samples. Because this fishery occurs on a foraging ground, animals of both sexes, as 
well as animals in various stages of reproductive immaturity and maturity can be 
examined. 

This study describes the reproductive cycle of male and female green turtles on a 
foraging ground based on morphometries and characteristics of the reproductive system. 
Testes and epididymides of males, and ovaries and oviducts of females were measured. 
The size of the organs and presence of sperm for males, and the size of the ovaries, 
characteristics of follicles, and presence of corpora lutea for females were used to 
describe the reproductive cycle. Reproductive recrudescence was correlated with 
environmental parameters. The reproductive status of animals harvested in the fishery 
provides information on the reproductive cycle of green turtles and will be used to aid in 
evaluating the impact of the current harvest. 

Methods 

Data Collection 

Green turtle reproductive tracts were examined opportunistically when animals 
landed in Puerto Cabezas, Nicaragua were butchered for sale in local markets (see 
Chapters 2 and 3 for details on the harvest). In order to include animals from the entire 
size range of harvested animals, each month I attempted to include a minimum of 10 



116 
harvested animals from each of the following four categories: "small" males, "large" 
males, "small" females, and "large" females. The cut-off between "small" and "large" 
was based on the size of the smallest nesting females at Tortuguero, Costa Rica. Animals 
smaller than 89.8 cm minimum straight carapace length (distance between the anterior 
edge of the nuchal scute and posterior notch) were categorized as "small". I was not 
always able to meet the minimum monthly sample size for each category because I was 
limited by the quantity of animals in each category landed in Puerto Cabezas, 
inaccessibility of several butchers, and the unwillingness of a few butchers to coordinate 
with me when animals would be butchered. 

Animals were measured and weighed the afternoon prior to the night in which 
they would be butchered. For each turtle, the following measurements were recorded: 
minimum straight carapace length (SLN) and body mass (WT). See Chapter 3 for a 
description of measurements. As animals were butchered, I collected testes and 
epididymides from males, and ovaries and oviducts from females. Measurements of the 
reproductive tracts were taken as soon as they were removed from the animal. For males, 
the following measurements were recorded: for each testis, maximum length, maximum 
width, maximum thickness, wet mass, and volume; and for each epididymis, wet mass 
and volume. 

For females, the following measurements were recorded: for each oviduct, 
infundibulum, tube, uterus, and total lengths; and for each ovary, wet mass and volume. 
The infundibulum was measured from the anterior end of the oviduct to the position 
where the outer walls of the oviduct became parallel. The tube was measured from the 



117 
posterior end of the infundibulum to the utero-tubular junction which was identified as a 
thickening in the oviduct wall. The uterus was measured from the utero-tubular junction 
to the utero-cloacal junction. In addition, the entire length of the oviduct was measured 
from the anterior infundibulum to the utero-cloacal junction. 

For each ovary, the number of macroscopically visible follicular size classes was 
recorded and the diameter of 10 representative follicles of the largest follicular size class 
present were measured. For each ovary, a mean diameter was calculated for the largest 
size class of follicles present. The presence or absence of corpora lutea were recorded. 
Length measurements were made with a 150-cm flexible tape measure to the nearest ± 
0.1 cm. Testicular width and thickness, and follicular diameter were measured with a dial 
caliper to the nearest ± 0.05 mm. Mass was measured with spring scales to the nearest ± 
0.5 gm and volume was measured by water displacement in a graduated cylinder to the 
nearest ± 1.0 ml. 

For males, minimum size at reproductive maturity was based on the presence of 
sperm in either the right testis or epididymis, with the exception of two males where the 
left testis and epididymis were used. A cross-section of testis and epididymis were 
flushed with a 10% saline solution and the effluent examined under a 400x simple 
compound microscope for the occurrence of sperm. A testicular sperm density index was 
developed for animals larger than the smallest animal with sperm. The presence of sperm 
was ranked based on a qualitative assessment using the following categories: no sperm = 
0, 1 sperm = 1, few sperm = 2, some sperm = 3, many sperm = 4, and packed with sperm 
= 5. Numerical codes for each animal were used to calculate mean sperm density, 



118 
rounded to the nearest ± 0.5, for each month. The larger the number, the more dense the 
number of sperm. 

For females, reproductive maturity was based on the number of follicular size 
classes, color of the largest follicles, and presence of corpora lutea. Color of the largest 
follicles were categorized as white, light yellow, yellow, or opaque yellow. Follicular 
color was used as an indicator of vitellogenic status; white indicates pre-vitellogenic, 
whereas, the three shades of yellow indicate progressively more advanced stages of 
vitellogenesis. When right and left follicular color differed, the color indicating the more 
advanced stage of vitellogensis was used. Minimum size at reproductive maturity was 
determined from examining histograms of the number of follicular size classes, follicular 
color, and presence of copora lutea with carapace length. 

Changes in testicular, epididymal, and ovarian measurements over time were used 
to determine reproductive seasonality. Only males larger than the smallest animal with 
sperm and females with a mean follicular diameter > 4.00 mm were used to determine 
reproductive seasonality. To account for differences in gonadal and epididymal 
measurements among animals due to different body sizes, a somatic index (SI) was 
calculated by dividing gonadal or epididymal measurements by live body mass (WT) and 
multiplying by a constant of 1000. 

Reproductive tracts were photographed and fixed in the field in 10% non-buffered 
formalin and stored in 70% ethyl alcohol at the University of Florida. All Nicaragua and 
CITES (Convention on International Trade in Endangered Species of Wild Fauna and 
Flora) permits were obtained. 



119 

Statistical Analysis 

Right and left gonadal, epididymal, and oviductal measurements of all animals 
were compared with a paired-difference t-test to determine if there was symmetry among 
male or female reproductive tissues. When there was no significant difference between 
right and left measurements a mean of the two measurements was used in subsequent 
analyses. When significant differences were found between right and left measurements, 
a Pearson correlation coefficient (PCC) was used to determine if right and left sides 
varied proportionally. Because sides did vary proportionally, a mean of the two 
measurements was used for subsequent analyses. 

The relationship between month and mean log testicular and epididymal 
measurements for males, and ovarian wet mass and volume for females was determined 
using analysis of covariance (ANCOVA), which included carapace length as a covariate 
(data were log transformed to achieve homoscedasticity, Sokal and Rohlf 1995). The 
assumption of equal variances among months was tested with Hartley's F max - test (Sokal 
and Rohlf 1995). For males, the assumption of equal variances was met for all 
measurements. For females, none of the measurements (diameter of the largest size class 
of follicles, ovarian wet mass and volume) met the assumption of equal variance. 
However, Scheffe (1959) has shown that linear relationships, such as analysis of variance 
(ANOVA) and ANCOVA, are robust without equal variances and thus, the assumption of 
equal variances for the ANCOVA was ignored. Analysis of variance was used to 
determine the relationship between month and mean log diameter of follicles in the 






120 
largest size class, carapace length was not included as a covariate because it was not 
significantly correlated with follicular diameter. 

Pearson correlation was used to determine if relationships exist between gonadal 
measurements and the following environmental parameters: mean monthly rainfall, and 
mean monthly minimum and maximum ambient temperatures. I recorded environmental 
parameters in Puerto Cabezas during the study period (see Chapter 3). 

All statistical analyses were conducted using SAS software (SAS Institute, Inc. 
1989). Univariate procedures were used to determine if distributions approximate 
normality and a t-test was used to test for equality of variances. When assumptions for 
parametric analyses were not meet and logarithmic transformation of the data still did not 
meet the assumptions, non-parametric tests were used, except in the case of the 
ANCOVA analysis. Means ± 1 S.E. are presented. 

Results 

Males 

Between November 1993 and January 1995 (15 mo), 264 male green turtle 
reproductive tracts were examined (see Table 4.1 for summary statistics). For males, 
mean minimum straight carapace length (SLN) was 87.0 cm ± 0.4 (range = 68.6 - 100.8 
cm, n = 262). Testes varied from oblong to long, thin strips that were either straight or 
curved. Epididymides tended to be irregular in shape with many lobes. In addition, 
many testes and epididymides contained various amounts of grey and black pigment. 



121 

Table 4.1 . Summary statistics for testicular and epididymal measurements for green 

turtles, Chelonia mydas, landed at Puerto Cabezas, Nicaragua from November 
1993 to January 1995. Reproductive tracts were examined during each month 
of the 15 -mo study period. Mean minimum straight carapace length for 
animals included below is 87.0 cm ± 0.4 (range = 68.6 - 100.8 cm, n = 262). 



Measurement 3 


Mean ± S.E. 


Range 


n 


TESTES 








Total Length (cm) 


22.8 ±0.30 


10.9-39.5 


257 


Maximum Width (mm) 


34.30 ±0.70 


13.28-73.08 


259 


Maximum Thickness (mm) 


6.84 ± 0.24 


1.80-24.30 


260 


Wet mass (gm) 


33.5 ±1.9 


3.7-210.0 


258 


Volume (ml) 


33.7±1.9 


3.5-200.0 


241 


EPIDIDYMIDES 








Wet mass (gm) 


21.3 ±0.8 


2.4 - 66.0 


236 


Volume (ml) 


20.1 ±0.8 


2.0-58.0 


236 



a Mean of right and left measurements. 

Right and left measurements for testicular wet mass, volume, maximum length, 
maximum width, maximum thickness, and epididymal wet mass and volume were 
significantly different (Paired-Difference t-test; P < 0.025 for all measurements). Since, 
right and left measurements were highly correlated (Pearson correlation coefficient, r > 
0.83, P < 0.0001 for all correlations) the mean of right and left testicular and epididymal 
measurements for each animal was used for all subsequent analyses. 

Males with the microscopic presence of sperm ranged from 79.6 cm SLN 
(harvested in June 1994) to 98.6 cm SLN (harvested in April 1994) (Figure 4.1A). The 
largest male (98.0 cm SLN) with no evidence of sperm was harvested in October 1994. 



122 



100% 



80% - 



60% 




40% 



20% 



68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 
Minimum Straight Carapace Length (cm) 



100% 



80% 



60%- 



40% 



20% 



Presence of Sperm E3 No M Yes 




MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 

1994 1995 



Figure 4.1. Presence of sperm (based on microscopic observation) in the right testis 
or epididymis of green turtles, Chelonia mydas, harvested from northeast 
Caribbean waters of Nicaragua, by A) minimum straight carapace lengh 
(SLN) and B) month of year for males ;> 80.0 cm SLN. Numbers on 
bars represent sample sizes. Turtles were landed in Puerto Cabezas, 
Nicaragua between November 1993 and January 1995. 



123 
Males with a SLN > 80.0 cm were considered mature, even though sperm were not 

observed in all of these males (Figure 4.1 A). Although one animal smaller than 80.0 cm 
SLN was observed with sperm, this represented only 8.3% of the animals in that size 
class, whereas, for all two-cm size classes ^ 80.0 cm SLN more than 30.0% of the males 
observed had sperm. For males > 80.0 cm SLN, sperm were observed in the testis or 
epididymis of animals harvested during every month of the year except September, 
though, males harvested in February were not examined for sperm (Figure 4. IB). During 
months of increased reproductive activity (April, May, and December 1994; and January 
1995, see below), sperm were not observed microscopically in 15.4% to 57.1% of the 
males > 80.0 cm SLN (Figure 4. IB). 

For mature males (SLN> 80.0 cm), an initial wave of testicular recrudescence 
(based on mean testicular wet mass) occurred in April and peaked in May 1 994 (Figure 
4.2A and B). A second period of testicular recrudescence began in December 1994 and 
was continuing when data collection ended in January 1995 (Figure 4.2A and B). In 
addition, mean monthly testicular sperm density corresponds with changes in testicular 
size (Figure 4.2). Mean epididymal wet mass did not exhibit seasonality (Figure 4.2A 
and B). An ANCOVA indicated there was a significant difference among months for 
mean testicular wet mass, after adjusting for carapace length (ANCOVA, F M>201 ■ 2.60; P 
= 0.001 8). Mean testicular wet mass was significantly different between May and 
September 1994 (Tukey, P = 0.022), May and February 1994 (Tukey, P = 0.0096), and 
approaches significance between February 1994 and January 1995 (Tukey, P = 0.056). 
Mean testicular width (ANCOVA, F 14 201 - 1.81; P- 0.040), mean thickness (ANCOVA, 



124 




NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 



TESTICULAR SPERM 
DENSITY INDEX 



Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan 



Mar Apr May Jun 



0.80- 
0.70- 



X 0.60- 
u 

« 0.50-1 
% 0.40- 



0.30- 



B 






Testes 
E2 Epididymides 













II 


1 1 It It 


I'' 1 "' 




\ 



NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 

1993 1994 1995 

Figure 4.2. Mean (± l S.E.) monthly testicular and epididymal A) wet mass and 

B) somatic indices, for green turtles, Chelonia mydas, > 80.0 cm minimum 
straight carapace length harvested from northeast Caribbean waters of 
Nicaragua. The testicular sperm density index is based on a qualitative 
assessment of mean monthly sperm density in the right testis. Increased 
sperm density is indicated by an increase in shading from light to dark. 
Turtles were landed in Puerto Cabezas, Nicaragua from November 1993 to 
January 1995. 



125 
F l4 200 = 3.26; P < 0.0001), and mean volume (ANCOVA, F 12> m = 2.46; P = 0.0052) 
exhibited a pattern similar to that of mean testicular wet mass (Figure 4.3 A and B, 
testicular volume not shown). Mean testicular length (ANCOVA, F 14 201 = 1 . 1 8; P = 
0.29) did not show seasonal patterns but remained relatively constant throughout the year 
(Figure 4.3A and B). Mean epididymal wet mass approached significance between 
January 1994 and January 1995 (ANCOVA, F 12 187 = 1.76; P = 0.058) and mean volume 
was significantly different for the same time period (ANCOVA, F 12- 1 88 = 1.95; P = 0.031) 
(Figure 4.2A and B, epididymal volume not shown). There was a significant difference 
between the SLN of males without sperm (x = 85.3 cm ± 1 .5, range = 68.6 - 94.6 cm, n = 
21) and those with sperm (x = 90.6 cm ± 0.9, range = 83.4 - 98.6, n = 22) (Wilcoxon 
Rank Sums, P = 0.020) during April and May, months when gonadal size changed the 
most. However, the size of some males without sperm were larger than those with sperm. 

For males with sperm, monthly mean testicular mass (PCC, r = -0.67, P = 0.034) 
and volume (PCC, r = -0.66, P = 0.037) were correlated with decreasing rainfall. Neither 
monthly mean testicular mass or volume were correlated with monthly mean minimum 
ambient temperature (PCC, r = -0.13, P = 0.71 for mass and r = -0.079, P = 0.83 for 
volume) or with maximum ambient temperature (PCC, r = 0.03 1, P = 0.93 for mass and r 
= 0.050, P - 0.89 for volume). 

Five males with apparently functional reproductive tracts were observed with 
incomplete oviducts. Mean SLN for these males was 91.8 cm ± 2.5 (range = 86.7 - 98.1 
cm, n = 4). Their oviducts varied from a short segment to several non-continuous 



126 




NOV DEC 
1993 



JAN FEB MAR APR 



MAY JUN JUL AUG SEP OCT NOV DEC JAN 
1994 1995 



0.14 



-0.12 



-0.08 




0.06 



0.02 



NOV DEC JAN 
1993 



l r 

FEB MAR 



APR MAY 



i r 

JUN JUL AUG 
1994 



SEP OCT NOV DEC 



JAN 
1995 



Figure 4.3. Mean (± 1 S.E.) monthly testicular measurements of green turtles, Chelonia 
mydas, ;> 80.0 cm minimum straight carapace length by A) maximum length, 
width, and thickness and B) somatic indices. Turtles were harvested from 
northeast Caribbean waters of Nicaragua and landed in Puerto Cabezas, 
Nicaragua from November 1993 to January 1995. 



2 
n 

3 

H 

a 



o 

7? 

3 



C/3 
O 

3 



-o.o4 =r- 



3 



127 
segments with each ending in a blind sac. Sperm was observed in two of the three 
animals examined; one of these contained sperm in only the testis, and the other 
contained sperm in both testis and epididymis. Testicular and epididymal measurements 
for these males were within the range of measurements recorded for males without female 
reproductive tissue. Testicular measurements were as follows: x length = 25.1 cm ± 2.1 
(range = 21.5 - 28.6 cm, n = 3), x width - 40.38 mm ± 4.76 (range = 31.20 - 47.13 mm, n 
= 3), x thickness = 1 1.90 mm ± 3.07 (range = 6.08 - 16.50 mm, n = 3), x wet mass = 57.2 
gm ± 19.1 (range = 20.5 - 84.3 gm, n = 3), and x volume = 54.2 ml ± 17.8 (range = 20.0 - 
80.0, n = 3). Epididymal measurements were as follows: x wet mass = 36.4 gm ± 10.0 
(range = 23.3 - 56.0 gm, n = 3) and x volume = 24.8 ml ± 3.3 (range = 21.5 - 28.0, n = 2). 



Between November 1993 and January 1995 (15 mo), 265 female green turtle 
reproductive tracts were examined (see Table 4.2 for summary statistics). For females, 
mean minimum straight carapace length (SLN) was 88.3 cm ± 0.5 (range = 70.5 - 107.5, 
n = 261). Ovaries varied from a firm to watery and flaccid texture, and the color varied 
from pink to transparent. Oviducts varied in color from white to pink. In addition, many 
oviducts had various amounts of grey and black pigment on the outer surface primarily 
along the tube and posterior uterus portions. No pigmentation was observed on the 
ovaries. There was no difference between right and left measurements for tube length, 
total oviductal length, and mean diameter of the largest size class of follicles (Paired- 
Difference t-test; P > 0.24 for each) and bordered on significance for uterus length 



128 

Table 4.2. Summary statistics for ovarian and oviductal measurements for green turtles, 
Chelonia mydas, landed at Puerto Cabezas, Nicaragua from November 1 993 
to January 1995. Reproductive tracts were examined during each month of 
the 15-mo study period. Mean minimum straight carapace length for animals 
included below is 88.3 cm ± 0.5 (range = 70.5 - 107.5 cm, n = 261). 



Measurement 3 


Mean ± S.E. 


Range 


n 


OVARIES 








Diameter of the largest size 


3.85 ±0.12 


0.98 - 20.20 


261 


class of follicles (mm) b 








Wet mass (gm) 


64.4 ± 4.3 


5.3-435.0 


256 


Volume (ml) 


63.7 ±4.5 


5.0-407.5 


230 


OVIDUCTAL LENGTHS 








Infundibulum (cm) 


8.1 ±0.5 


0.5 - 37.0 


251 


Tube (cm) 


156.5 ±7.9 


25.0-498.0 


220 


Uterus (cm) 


87.1 ±4.2 


7.8 - 340.5 


226 


Total (cm) 


234.1 ±12.1 


43.0-903.5 


247 



Mean of right and left measurements. 
b Based on the mean often representative follicles. 



(Paired-Difference t-test; P = 0.068). Right and left measurements for ovarian wet mass 
and volume, infundibulum length, and mean number of follicular size classes were 
significantly different (Paired-Difference t-test; P < 0.022 for each). Since right and left 
measurements were highly correlated (PCC, r > 0.95, P < 0.0001 for each), I used the 
mean of right and left ovarian and oviductal measurements for each animal for all 
subsequent analyses. 

Mean number of macroscopic size classes of follicles ranged from zero to seven 
(x - 3.1 ± 0.05, n = 261). Ovaries of the majority (59.9%) of females had a mean of three 



129 
size classes of follicles, and all but three females had a mean of at least two follicular size 
classes. Ovaries of smaller females had fewer size classes of follicles than larger females, 
although none of the largest animals had the greatest number of follicular size classes 
(Figure 4.4). Ovaries of females < 85.0 cm SLN contained from no macroscopically 
visible follicles to a mean of four follicular size classes. Females ^ 91.0 cm and < 101.0 
cm SLN contained up to seven size classes of follicles (Figure 4.4). 

Larger females exhibited more advanced stages of vitellogenesis (Figure 4.5A). 
Females < 75.0 cm SLN did not exhibit vitellogenic activity and none of the females < 
83.0 cm SLN exhibited the most advanced stages of vitellogenesis based on the color of 
the largest size class of follicles. However, females that were > 83.0 cm SLN were in 
varying stages of vitellogenesis, as well as, non-vitellogenic (Figure 4. 5 A). 

Only two of the 265 females examined contained shelled eggs in their oviducts. 
One female, landed at Puerto Cabezas on 17 November 1993, contained eight shelled 
eggs at the distal end of the left oviduct. Egg diameters ranged from 41.60 to 45.10 mm 
(43.14 mm ± 1.15, n = 8). The other female, landed at Puerto Cabezas on 26 July 1994, 
contained one shelled egg in the lower right oviduct. The diameter of this egg was 43.25 
mm. The egg shell surface was rough and crusty. 

A greater percentage of the larger females have macroscopic copora lutea, 
evidence that they have ovulated. No corpora lutea were observed macroscopically on 
ovaries of females < 87.0 cm SLN and as large as 100.9 cm SLN indicating ovulation had 



130 



100% 



80% - 



60% 



40% 



20% 



0% -\ i r i i i i i i r i — i — i — i — r 

69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 




Minimum Straight Carapace Length (cm) 



MEAN NUMBER OF FOLLICULAR SIZE CLASSES (SC) 
D osc □ 1 sc E3 2 sc ED 3 SC H 4 SC Q 5 SC ■ 6 sc ■ 7 SC 



Figure 4.4. Mean number of follicular size classes of right and left ovaries by minimum 
straight carapace length of green turtles, Chelonia mydas. Animals were 
harvested from northeast Caribbean waters of Nicaragua and landed in Puerto 
Cabezas, Nicaragua from November 1993 to January 1995. Numbers on bars 
represent sample sizes. 






100% 



80% - 



60% - 




131 



40% 



20% 



i i r 

69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 
Minimum Straight Carapace Length (cm) 



FOLLICULAR COLOR 
D White E2 Light Yellow ^ Yellow ■ Opaque Yellow 




69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 
Minimum Straight Carapace Length (cm) 



PRESENCE OF CORPORA LUTEA Q No 



Yes 



Figure 4.5. Follicular color (A) and presence of corpora lutea (B) for the right and left 
ovaries of green turtles, Chelonia mydas, by carapace length. Turtles were 
harvested from northeast Caribbean waters of Nicaragua and landed in 
Puerto Cabezas, Nicaragua from November 1993 to January 1995. 
Numbers on bars represent sample sizes. 



132 
not occurred, at least not recently (Figure 4.5B). All ovaries of animals > 101.0 cm and < 
109.0 cm SLN had corpora lutea. 

Based on an examination of the number of follicular size classes, follicular color, 
and presence of corpora lutea by carapace length, nearly all females < 89.0 cm SLN were 
reproductively immature. Therefore, reproductive seasonality based on the mean number 
of follicular size classes and follicular color was examined using only females > 89.0 cm 
SLN. Mean number of follicular size classes varied seasonally, although in all months 
females had at least two follicular size classes, the majority (52.2%) had three (Figure 
4.6A). In April 1994, 36.4% and in January 1995, 60.0% of the females had ovaries with 
five to seven follicular size classes. 

Based on follicular color, mature females are in varying degrees of vitellogenesis 
each month of the year (Figure 4.6B). Although a highly distinct pattern does not appear, 
females with follicles in more advanced stages of vitellogenesis occurred between July 
and October 1994. Females with the least reproductive activity occurred in the months of 
February, May, and June 1994. 

To examine reproductive seasonality based on mean diameter of the largest size 
class of follicles, and ovarian wet mass and volume, only females with a mean follicular 
diameter > 4.00 mm for the largest size class (Size Class I) were examined (based on 
Limpus and Reed 1985a). Ovarian recrudescence (based on mean diameter of Size Class 
I follicles, and mean ovarian wet mass and volume) occurred in March and peaked in 
April 1994. A second period of ovarian recrudescence began in December 1994 and was 



100% 



A) 



133 



80% - 



60% 



40% - k 



20% - > 



0% 



III 


I 


1 

/// 




3. 

§ 


1 

2 



4 

I 


III 
III 


ill 


4 


ill 

Li±Kj 


III 
iii| 


4 

til 


1 

i 




! 

2 | 
111 



NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 



MEAN NUMBER OF FOLLICULAR SIZE CLASSES (SC) 
E2 2SC OH 3SC HH 4SC ■ 5SC ■ 6SC ■ 7SC 



100% -az 




NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 

1993 1994 1995 



FOLLICULAR 
COLOR 



□ White E3 Light Yellow ^ Yellow B Opaque Yellow 



Figure 4.6. Mean number of follicular size classes (A) and follicular color (B) by 
month for green turtles, Chelonia mydas, > 89 cm minimum straight 
carapace length. Turtles were harvested from northeast Caribbean waters 
of Nicaragua and landed in Puerto Cabezas, Nicaragua from November 
1993 to January 1995. Numbers on bars represent sample sizes. 



14 



12- 



E 

e 
— 
I 



=5 
O 



O 



10 



8- 



Q Follicle | Ovary Mass |H Ovary Volume 





i i i i i i i i i i i i r 

NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 



250 



2 



200 



150 I 



100 



50 



1993 



1994 



1995 



< 

c 
3 
a 



134 



0.10- 



u 

■o 0.08H 



B 



Q Follicle 



Ovary Mass 




^2.0 | 




i i I l i r 

NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 

1993 1994 1995 



Figure 4.7. A) Mean (± 1 S.E.) monthly diameter of the largest follicular size 

class, mean ovarian wet mass and volume and B) somatic indices, for 
green turtles, Chelonia mydas, with the largest size class of follicles 
^ 4.0 mm. Turtles were harvested from northeast Caribbean waters 
of Nicaragua and landed in Puerto Cabezas, Nicaragua from November 
1993 to January 1995. Standard error bars are shown when sample 
size is greater than one. 



135 
continuing when data collection ended in January 1995 (Figure 4.7A and B). An 
ANOVA indicated there was a significant difference among months for the mean log 
diameter of Size Class I follicles (ANOVA, F l3 55 = 2.21; P - 0.021). Mean log diameter 
of Size Class I follicles was significantly different between August 1994 and January 
1995 (Tukey, P = 0.047) and approached significance between November 1994 and 
January 1995 (Tukey, P = 0.052). Although mean log ovarian wet mass and volume 
exhibited a similar reproductive cycle as follicular diameter, an ANCOVA indicated there 
was no significant difference among months for either ovarian wet mass (ANCOVA, F 13 
52 = 0.78; P - 0.68) or volume (ANCOVA, F u 48 = 0.81; P = 0.63). 

Mean diameter of the largest size class of follicles (for females with follicular 
diameter > 4 mm) was correlated with decreasing monthly rainfall (PCC, r = -0.67, P = 
0.035). Mean ovarian wet mass and volume (PCC, r = -0.70, P < 0.024, for each) were 
correlated with decreasing monthly mean minimum ambient temperature. Mean diameter 
of Size Class I follicles was not correlated with either monthly minimum (PCC, r = -0.35, 
P = 0.32) or maximum (PCC, r = -0. 1 8, P = 0.62) ambient temperatures. Monthly mean 
wet mass and volume were not correlated (PCC, r < -0.56, P > 0.09, for each) with either 
monthly rainfall or maximum ambient temperature (PCC, r < -0.51, P > 0.14, for each). 

Discussion 

Based on tag recoveries (Carr et al. 1978) and mitochondrial DNA (mtDNA) 
analysis (Bass et al. in press) the principal rookery, for adult-size green turtles found on 
the Nicaragua foraging ground is Tortuguero, Costa Rica. The green turtle nesting season 



136 
at Tortuguero is from June to October with peak nesting from July through September 
(Carr et al. 1978). Mating occurs during nesting migrations (P. Meylan et al. 1992) and 
in the vicinity of the nesting beach (Carr 1954, 1956; Carr and Ogren 1960; Carr et al. 
1978; Mortimer 1981; Hirth 1997). Although specific migratory movements have not 
been described, reproductively active males and females occur in waters off the nesting 
beach (Carr 1956; Carr and Ogren 1960; Carr et al. 1978; Ross and Lagueux 1993; Hirth 
1997); thus, each season, both male and female breeding animals leave the foraging 
ground. 

Not all adult-size males on the Nicaragua foraging ground are annual breeders, 
although they can breed annually (Balazs 1983; Limpus 1993). Males as large as 98.0 cm 
(minimum straight carapace length, SLN) had no microscopic evidence of sperm. Not all 
males > 80.0 cm SLN had sperm during months of reproductive activity nor did any of 
the 10 animals (SLN > 80.0 cm) examined in September, suggesting that none of these 
males bred during the current reproductive season. Recapture intervals of 1-5 yr of 
tagged males in the Hawaiian Islands (Balazs 1983) and in Australia (Limpus 1993) also 
suggest that males are not annual breeders. However, not all males attain sexual maturity 
at a minimum size (Limpus 1990, Limpus et al. 1994a, b). Determining breeding 
intervals based on recaptures of tagged animals should be viewed with caution because 
tag loss can be high (Limpus 1992b; Bjorndal et al. 1996) and recapture rates are not 
100%. Identifying the proportion of annual breeders in a population is necessary to avoid 
overestimating the size of the breeding population. 



137 
Seasonal reproductive activity was not observed in all testicular, epididymal, 
ovarian, and oviductal measurements. For males, the greatest seasonal change occurred 
in mean testicular mass, volume, and thickness. Mean testicular length, and epididymal 
mass and volume were the poorest indicators of seasonality. For females, the greatest 
seasonal change occurred in the mean diameter of the largest size class of follicles (for 
females with follicles > 4.00 mm). Mean ovarian mass and volume also exhibited 
seasonal changes, but not to the same extent as follicular diameter. 

Right and left measurements of tube length, total oviductal length, and mean 
diameter of the largest size class of follicles did not differ significantly. Thus, either right 
or left measurements would be sufficient for future studies. All other measurements 
differed significantly, ovarian wet mass and volume; infundibulum and uterus lengths; 
number of follicular size classes; testicular wet mass and volume; maximum testicular 
length, width, and thickness; and epididymal wet mass and volume. Although they 
differed significantly, they did so proportionally, within the size range of the animals 
examined. Therefore, it is necessary to either measure both sides of the animal and report 
the mean, or, if only one side is measured, the side measured should be consistently 
reported. Otherwise, comparisons of reproductive tract measurements should not be 
made among studies. 

The synchronization in the peak and nadir of reproductive activity throughout the 
year for males and females is very similar. Green turtles in Nicaragua have a prenuptial 
cycle, as previously reported for captive males (Licht et al. 1985), migrating males 
(Engstrom 1994) and loggerheads, Caretta caretta, (Wibbels 1988; Wibbels et al. 1990). 



138 
That is, sperm production and vitellogenesis are completed just prior to mating (Licht 
1984). The annual gonadal cycle agrees with the plasma testosterone cycle of a captive 
breeding colony (Licht et al. 1985). This contrasts with the postnuptial cycle reported for 
many temperate species of freshwater turtles (Moll 1979; Licht 1982). Measures of 
ovarian activity (i.e., mean follicular diameter, ovarian mass and volume) peaked in April 
for females, whereas, testicular activity (i.e., mean mass, volume, width, and thickness) 
peaked in May for males. Both ovarian and testicular measurements were increasing in 
December 1994 and January 1995, when the study ended, at levels equal to the April and 
May 1994 peaks. Due to a sharp decrease in gonadal measurements, it appears that 
reproductively active females left the northeast foraging ground of Nicaragua for the 
nesting beach at Tortuguero in May, whereas, males left in June. It is unknown, however, 
if males and females arrive separately at the nesting beach, rejoin each other along the 
migratory route, or migrate separately but synchronize their arrival at the nesting beach 
(Hirth 1997). Because only animals from the northern extent of the Nicaragua foraging 
area were examined, it is possible that animals foraging on the southern Nicaragua 
grounds (i.e., located offshore between the communities of Sandy Bay Sirpi and Set Net, 
see Figure 2.1) show a different migratory schedule. 

During this study, gonadal recrudescence occurred at two different time periods 
for both males and females. Gonadal size peaked in April 1994 for females and in May 
1994 for males, and was increasing for both sexes in December 1994 and January 1995. 
It is notable that the increase in gonadal activity that occurred in December 1994 and 
January 1995 for both sexes was not observed during the beginning of the study in 



139 
December 1993 and January 1994. The difference observed in the onset of gonadal 

activity during the study can be hypothesized to be due to a shift in reproductive 
recrudescence as a response to a change in environmental cues (Duvall et al. 1982; Crews 
and Gans 1992; Whittier and Tokarz 1992) or due to sampling animals from rookeries 
with different nesting seasons. 

Yearly shifts in the onset of reproductive activity can be caused, in part, by 
variability in the onset of environmental parameters from year to year, e.g., precipitation 
and temperature. There is a significant correlation between the El Nino Southern 
Oscillation (ENSO) and the number of nesting females at Heron and Raine Islands, 
Australia approximately two years later (Limpus and Nicholls 1988). The ENSO is a 
combination of pressure, temperature, and rainfall fluctuations. In Nicaragua, testicular 
mass and volume, and diameter of the largest follicular size class were correlated with 
decreasing rainfall, and ovarian mass and volume were correlated with decreasing 
minimum ambient temperature. Because exogenous factors affect seasonal movements 
on the grassbeds, they can also play a role in stimulating or delaying reproductive 
activity. During the rainy season turtles forage on grassbeds located further from shore to 
avoid the discharge of silt laden freshwater from numerous river mouths that can extend 
16 to 18 km from the coast (Nietschmann 1973; Mortimer 1981). Therefore, changes in 
the onset of environmental cues, e.g., rainy season, can cause a shift in reproductive 
recrudescence possibly accounting for the difference observed between the years. 

Another explanation for observing reproductive activity during different times in 
the study period could be due to examining animals from rookeries with different nesting 



140 
seasons. Based on tag recoveries and mtDNA analysis of adult-size males and females, 
the Nicaragua foraging ground population comprises animals from at least two different 
rookeries, Tortuguero Costa Rica (Carr and Ogren 1960; Carr et al. 1978; Bass et al. in 
press), and Aves Island, Venezuela (Sole 1994; Bass et al. in press). The green turtle 
nesting seasons for these rookeries are: June to October for Tortuguero (Carr et al. 1978) 
and February to November for Aves Island (Licht et al. 1980; Pritchard 1984; Sole and 
Medina 1989). The reproductive activity observed for some of the animals harvested in 
December 1 994 and January 1 995 could have been from the Aves Island rookery whose 
nesting season begins four months prior to the nesting season at Tortuguero. The absence 
of reproductively active animals in the December 1993 and January 1994 samples can be 
explained by the low probability of sampling animals from rookeries other than 
Tortuguero, such as Aves Island, because 1 ) male and female green turtles are not annual 
breeders (Carr et al. 1978; this study) and thus, there is a small proportion of mature 
animals reproductively active each season on the foraging ground, and 2) the northern 
extent of the foraging ground is comprised of a high proportion (90%) of adult 
Tortuguero animals (Bass et al. in press), further reducing the probability of sampling 
reproductively active Aves Island turtles. 

Few studies have reported on the morphometries of organs and structures 
associated with sea turtle reproductive systems (Aitken et al. 1976; Solomon and Baird 
1979; Owens 1980; Licht et al. 1985), and fewer have described seasonal morphometric 
changes with which comparisons can be made (Licht et al. 1985). In this study, mean 
diameter of the largest follicular size class (20.2 mm) did not approach the size of 



141 
follicles measured just prior to ovulation (30 - 35 mm; Aitken et al. 1976; Solomon and 
Baird 1979). This suggests that females depart the northern extent of the Nicaragua 
foraging ground toward the nesting beach prior to ovulation. This hypothesis is further 
supported by the absence of eggs in the oviducts. Only two females were observed with 
one and eight shelled oviductal eggs. These eggs were probably retained from a previous 
nesting event as opposed to being shelled in preparation for an upcoming nesting event. 
Egg diameters (41.60-45.10 mm) were within the range reported for eggs laid at the 
Tortuguero, Costa Rica rookery (range = 39.1 - 48.4 mm, Bjorndal and Carr 1989). 

None of the testes observed during this study attained a mass equal to two of the 
three (individual animals) testes observed from green turtles harvested nearly twenty 
years ago from the same area in Nicaragua (Owens 1980). The largest testicular mass I 
recorded was 210.0 gm, which occurred in April 1994, compared to 237.1 gm and 365.9 
gm, also for April 1976, reported by Owens (1980, in litt.). Using a gonadal somatic 
index (GSI) to account for the effect of carapace length on testicular mass, the males 
observed by Owens (1980) had GSIs of 3.42 and 2.35 compared to 2.18 and 1.88 for the 
two males with the largest testicular mass and GSIs observed in this study. First-time 
nesting females lay fewer clutches (Limpus 1 996) and fewer eggs per season (Carr and 
Ogren 1960; Carr et al. 1978; Fowler 1979; Frazer 1984; Limpus 1996) than more 
experienced nesters. If males follow the same pattern as females, then the lower GSIs 
(compared with Owens 1980) observed in this study could indicate that the more 
experienced breeders are less abundant than 20 years ago (Owens in litt.). 



142 
Conclusions 

The Nicaragua green turtle fishery includes large juveniles, novice and mature 
breeders of both sexes. The life stages targeted by the fishery are the most valuable 
animals to a population in terms of maintaining population stability. For unharvested 
populations, survival rates of large juveniles and adults of long-lived, slow-maturing, 
iteroparous species are necessarily high to maintain stable populations (Congdon and 
Dunham 1994). Green turtles can take from 20 to 60 years to reach sexual maturity 
(Limpus and Walter 1980; Mendonca 1981; Burnett-Herkes et al. 1984; Frazer and 
Ehrhart 1985; Zug and Balazs 1985; Frazer and Ladner 1986). The majority of animals 
captured in the fishery are harvested after they have almost survived the 20 or more years 
needed to attain reproductive maturity, thus eliminating any reproductive and genetic 
contributions they could have made to future populations. 

Many nesting studies (Carr et al. 1978; Balazs 1980, 1983; Limpus and Reed 
1985a; Mortimer and Carr 1987; Hirth 1997 for a review) have confirmed that females 
take multiple years between nesting events and it appears that at least some males can 
also take more than one year between breeding events (Balazs 1980, 1983; Limpus 1993; 
this study). In addition, more experienced breeding males could be less frequent than in 
the past, suggesting that this segment has been harvested out of the population. The 
fishery should be managed to allow as many individuals as possible to reach full 
reproductive maturity. 



143 
If a green turtle harvest is to continue, then it must be understood that the fishery 
removes the animals most valuable to the population as indicated by the life stages 
targeted in the fishery (this study) and their apparent importance to population growth 
(Crouse et al. 1987; Congdon et al. 1993, 1994; Congdon and Dunham 1994; Crowder et 
al. 1994; Heppell et al. 1995; Heppell et al. 1996a, b). More research is needed to 
thoroughly evaluate the impact of the fishery on the turtle population, however, measures 
should be adopted now to mitigate possible impacts to the turtle population. One 
measure would be to lower the annual harvest levels of green turtles. Another measure 
would be to regulate the size and sex of animals harvested. Although all animals 
harvested are valuable to population growth it might be less detrimental to the population 
to harvest a larger proportion of males and specifically, harvest the larger males. Because 
sea turtles are polygynous, one male can fertilize several females (Limpus 1993). By 
harvesting larger males this would allow them the opportunity to mate and pass on their 
genetic lineage prior to being harvested, however selective harvesting as suggested here 
should be approached cautiously. Harvest levels will need to be regulated and monitored 
because we lack knowledge about the role of accessory males in accompanying or 
attending mating pairs (Carr 1956; Carr and Giovannoli 1957; Hendrickson 1958; Booth 
and Peters 1972; Balazs 1980; Limpus 1993). It is likely that a combination of strategies 
will be needed to regulate the Nicaragua harvest and maintain a viable foraging 
population of green turtles for future generations of coastal residents. 



CHAPTER 5 

ASSESSMENT OF HARVEST LEVELS AND THEIR 

IMPACT ON MARINE TURTLE POPULATIONS 



Introduction 

The Nee d to Evalua te the Nicaragua Marin e Turtle Fish er y 

Worldwide, marine turtles are endangered due to hundreds of years of harvesting 
animals and their eggs (see review of worldwide exploitation in Chapter 1), primarily for 
meat and tortoiseshell, but also for oil and calipee, and most recently due to habitat 
destruction or alteration, and incidental capture (Parsons 1962, 1972; Bjorndal 1982; 
National Research Council 1990; Lutcavage et al. 1997). Throughout the greater 
Caribbean, green {Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtle 
populations have declined from the abundant levels described by early Europeans on their 
arrival to the New World (Carr 1954; Parsons 1962, 1972; Bjorndal et al. 1993; Meylan 
1997a). Today, Nicaragua has the largest remaining green turtle foraging population in 
the Atlantic Ocean (Carr et al. 1978). 

Juvenile and adult green turtles tagged in at least eight countries (Sole 1994; 
Bjorndal and Bolten 1996; Bagley in lift.; Bresette in lift.; Meylan in lift.; Ehrhart pers. 
com.; Moncada pers. com.; Lagueux pers. obs.), and hawksbills tagged in at least three 
countries (Carr et al. 1966; Carr and Stancyk 1975; Bjorndal et al. 1985; Hillis 1994; 

144 



145 
Garduno in lift.; see Meylan 1997b for review) throughout the greater Caribbean have 
been harvested in Nicaragua waters. Two loggerheads {Caretta caretta) one tagged in 
Panama (Meylan in litt.) and one in the Azores, Portugal (Bjorndal in lift.) were also 
recovered in Nicaragua. Because sea turtles move through several developmental 
habitats (Musick and Limpus 1997) and adults migrate between nesting and foraging 
grounds (Meylan 1 982), the Nicaragua marine turtle fishery can impact turtle populations 
shared by several nations, across great distances. In addition, conservation efforts 
enacted by other nations in the Caribbean to protect sea turtles could be diminished or 
nullified by an overharvest of turtles in Nicaragua. 

The central government has established seasonal regulations to control the harvest 
of green turtles off Nicaragua's Caribbean coast, however, they are unclear, unenforced 
and ineffective (Nietschmann 1973; Peralta Williams 1991; D. Castro pers. com.; C. 
Lagueux pers. obs.). The closed season has at different times varied in duration and 
included a total ban against the harvest of turtles, a ban against the commercialization of 
marine turtles, and a ban against the harvest of females (Nietschmann 1972, 1973; Weiss 
1976; Montenegro Jimenez 1992). Despite these regulations the turtle harvest continues 
unabated throughout the year. The turtle fishery is neither managed by the central or 
regional governments nor by Miskitu Indian taboos or restrictions against the harvest or 
consumption of marine turtles (D. Castro pers. com.; M. Grantt pers. com.; V. Renales 
pers. com.). It is imperative to evaluate this fishery and its possible impact on marine 
turtle populations in the region because: 1) sea turtles are an important economic and 
cultural resource to the Miskitu Indians; 2) the Nicaragua green turtle foraging population 



146 
is the largest in the western Atlantic (Carr et al. 1978); 3) sea turtles are a shared 
international resource; 4) evidence from elsewhere suggests that sea turtles can be readily 
fished to extinction; and 5) there are no provisions currently in Nicaragua to protect 
against overharvest. 

A pproaches to Ev aluating Biological Suslainability 

There are several approaches to evaluating the biological sustainability (i.e., the 
ability of the population to maintain itself over time) of harvesting a resource such as 
marine turtles. Monitoring population size for changes caused by harvesting is one 
approach that requires a comparison of population estimates at different time periods. 
Population size or density is usually determined by sampling some portion of the 
population because a complete population census is rarely possible. Population estimates 
can be based on direct or indirect sampling (Caughley 1977; Davis and Winstead 1980; 
Caughley and Sinclair 1994). Common direct sampling methods include counting 
animals observed on transects of known area and through mark/recapture methods. 
Indirect sampling methods use evidence of animal presence, e.g., counting tracks, scats, 
or calls, per a unit of area or time. Furthermore, the population's rate of increase (r) can 
be determined from these population estimates. The resulting r indicates if the 
population is increasing, decreasing, or stable and thus, can provide an indication of 
overharvest (Caughley and Gunn 1996). An alternative method to estimating r is through 
modeling population behavior based on demographic parameters of the population 



147 
(Caughley and Gunn 1996). However, the data needed (e.g., survival rates, fecundity, 
and population counts) to determine r by either method can be difficult to obtain. 

Another approach to assessing biological sustainability is to compare a 
population's maximum rate of increase (r m ) to the proportion of the population harvested 
annually. If the proportion harvested annually exceeds rJ2 for a population at K/2, 
where K is the average size of the unharvested population (Caughley and Sinclair 1994), 
then the maximum sustained loss of the population is exceeded and the population will 
decline. 

A third approach is to assess trends in parameters of the harvest and the harvested 
animals as indicators of the sustainability of the harvest. This approach provides an 
alternative when many population parameters are not available. Some indices that can be 
monitored are size and age distributions of harvested animals and capture per unit effort 
(CPUE). Although less desirable than monitoring population size directly, estimating 
and monitoring parameters of the harvest over time is the only approach for species 
whose populations are logistically difficult to sample, such as, sea turtles and seahorses 
(Vincent 1996). 

Even when demographic parameters can be estimated, confidence in assessing 
sustainable take is often low due to unreliable estimates and lack of a thorough 
understanding of population dynamics. For example, Marsh (1997) evaluated the 
sustainability of a dugong fishery and although she estimated population parameters from 
many years of data collection, she was still unable to determine the sustainability of the 
fishery due to lack of essential data. 



148 
Biological Sust ainah ility of the Marine Turtle Fishery 

The sustainahility of the Nicaragua marine turtle fishery can not be evaluated at 

this time by using population parameters because most of these data are not available. 

The data necessary to do a thorough evaluation of the biological sustainahility of the 

fishery include harvest patterns, population estimates, and life history parameters. Only 

data on the fishery are available at this time, and therefore, an evaluation of harvest 

parameters and the harvested animals is the only approach available to provide some 

assessment of the biological sustainahility of the fishery on the turtle populations. There 

are no published rigorous assessments on the biological sustainahility of harvesting green 

turtles. I assessed the effect of the Miskitu Indian marine turtle fishery on green turtles 

and hawksbills by integrating my results on harvest rates, CPUE, and demographic 

parameters of harvested animals. The effect of the fishery on loggerhead and leatherback 

{Dermochelys coriacea) populations were not assessed because sufficient data from the 

fishery are not available at this time. 

Methods 

I used results from Chapters 2, 3, and 4; and comparisons of current harvest 
patterns with historical information about the fishery to assess the biological 
sustainahility of the fishery. For green turtles, I categorized results as either not 
indicating overharvest or indicating overharvest for the following trend analyses: 1) the 
annual harvest rate for all sites combined and monthly harvest rates; 2) CPUE; and 3) size 
of harvested animals. For hawksbills, I review trends in monthly harvest levels and 



149 
compare them with historical harvest levels. No data are available on CPUE of 
hawksbills because their harvest is opportunistic during other activities, e.g., green turtle 
and lobster fisheries, and human presence on offshore cays and mainland nesting beaches. 
The evaluation of the impact of the fishery on Nicaragua marine turtle populations is 
preliminary because of the relatively short time period for which data are available and 
because of the indirect nature of available data. 

Results 

Green Turtles 

Indicato rs that do n ot suggest overh arvestin g 

From 1994 to 1996 the number of turtles killed/yr has remained relatively 
constant at approximately 10,000 to 1 1,000, based on landings at eight data collection 
sites. The trend in monthly harvest levels has remained relatively constant for all RAAS 
communities combined over a 2.5-yr period (P = 0.29), and for one RAAS community 
(Sandy Bay Sirpi) over a 6-yr period (P = 0.78). There has been no significant change in 
the net capture/unit effort (N-CPUE) in the RAAN over 13 mo (P = 0.36), in the RAAS 
over 17 mo (P = 0.85), or in one RAAS community (Sandy Bay Sirpi) for 48 mo of a 72- 
mo period (P = 0.22). No change in either N-CPUE or in harvest levels suggests that 
capture effort has not increased and that population levels have not, as yet, changed to the 
extent that they alter CPUE. For turtles landed in the RAAN at Puerto Cabezas (PC), 
Awastara (AW), and Sandy Bay (SB), the change in mean plastron lengths of < 0.5 cm 



150 
for the 3.25-yr period was not significant (P ^ 0.12 for the three sites; n = 3,886 for PC; n 
= 1,491 for AW; and n = 2,088 for SB). 
Indicator s that suggest overharvestin g 

For turtles landed at four data collection sites in the RAAS, the mean plastron 
length decreased significantly by 4.6 cm over the 2.5-yr period (P < 0.0001, n ■ 8,371). 
Mean body mass of turtles (n = 1,438) landed in Puerto Cabezas in 1992/1993 was 10 kg 
less than turtles landed at one Miskitu village in 1968 (Nietschmann 1972, 1973; sample 
size not provided), a period prior to the Nicaragua processing plants. In recent years, in 
both the RAAN and RAAS, some turtlers reported decreasing the mesh size of their nets 
in order to catch smaller animals (V. Renales pers. com.; P. Julias pers. com.). 

Hawksb ill Turtles 

Monthly harvest levels of hawksbills appear to have remained relatively constant 
from 1993 to 1996. Compared with the early 1970s (Nietschmann 1972, 1973), however, 
there has been a 479% decrease in the harvest rate of hawksbills by one Miskitu village. 

The data available, to date, on the fishery and harvested animals do not indicate 
conclusively whether or not the green turtle population is overharvested. Trend analyses 
on the size of harvested animals in the RAAN, N-CPUE, and monthly harvest rate in the 
RAAS do not indicate at this time that the foraging population is in decline. All analyses, 
however, were conducted over very short time periods (from 13 mo for the trend in 



151 
plastron length and CPUE to 72 mo for monthly harvest rates for one community in the 
RAAS), probably too short to detect changes in the population if they occurred. The 
significant decrease in mean plastron length of animals harvested in the RAAS during 
this study, however, is similar to one of several observations made twenty years ago, 
when harvest levels on the foraging ground were similar to current levels. At that time, 
researchers reported a decrease in the capture of larger animals, as well as a decrease in 
CPUE and a decrease in the nesting density of females at the Tortuguero rookery 
(Nietschmann 1972,1973, 1976, 1979a; Weiss 1976; Carrpers. com. to Nietschmann 
1976). 

The difference in results of the trend analyses for plastron length in the RAAN 
and RAAS is possibly due to differences in immigration rates of animals in the north and 
south regions compared to their respective harvest rates. The decrease in size of 
harvested animals in the RAAS could indicate that animals are immigrating onto the 
south foraging ground at a lower rate than they are harvested. The use of CPUE as an 
estimate or indicator of abundance can be problematic due to the relationship of CPUE 
and resource abundance (Hilborn and Walters 1992). In fisheries where search is highly 
efficient, the most effort is concentrated in areas where fish are abundant, resulting in 
hyperstability, a condition where CPUE remains high as fish abundance declines (Hilborn 
and Walters 1992). Thus, CPUE for the turtle harvest could remain unchanged while the 
turtle population is declining. At this time, the trend analysis on plastron length may be 
the best indication of the fisheries impact on the turtle population. The change in size in 



152 
the RAAS particularly over a relatively short time period suggests that overharvest is 

occurring. 

T urtle Life Histo r y Traits an d their Implications for Exploitation 

In addition to the decrease in size of harvested animals in the RAAS, which 
suggests overharvesting, the life history traits of the species also suggest they could easily 
be overharvested. Sea turtles are long-lived, large-bodied marine vertebrates. They are 
slow to reach sexual maturity, surviving many years before reproducing. They lay 
several clutches within a season and many clutches throughout their reproductive life 
which is necessitated by high mortality of eggs and hatchlings. Thus, high survival of 
juveniles and adults is necessary to maintain stable populations (Congdon and Dunham 
1994). The combination of these life history traits limits the ability of sea turtle 
populations to respond to chronic increases in juvenile or adult mortality through human- 
induced mortality, such as harvesting (Congdon et al. 1993, 1994; Congdon and Dunham 
1994). Population modeling of loggerheads (Crouse et al. 1987; Crowder et al. 1994; 
Heppell et al. 1996a), hawksbills (Heppell et al. 1995), Kemp's ridleys, Lepidochelys 
kempi, (Heppell et al. 1996b), and several freshwater turtles species {Kinosternon 
flavescens, Heppell et al. 1996b; Emydoidea blandingii, Congdon et al. 1993; Chelydra 
serpentina, Congdon et al. 1994) has shown that survival of juveniles and adults must 
remain high to maintain stable populations of long-lived, slow-maturing, iteroparous 
species. 



153 
The sizes of green and hawksbill turtles harvested in the Nicaragua fishery 
indicate that they are mostly large juveniles or adults (this study). This conclusion is 
based on the relationship between the sizes of the animals harvested and the minimum 
sizes recorded for nesting females at the primary rookery Tortuguero, Costa Rica (see 
Chapter 3), the smallest males observed with sperm, and the smallest females observed 
with corpora lutea (for green turtles only; see Chapter 4). If the conclusions drawn from 
studies on population modeling for long-lived, slow maturing species, as summarized 
above, are valid for green and hawksbill turtles in Nicaragua, then the greatest pressure 
from the Miskitu Indian marine turtle fishery is on the life stages that are least able to 
withstand the effects of exploitation. 

Green Turtles 

Current regional perspective 

In addition to the harvest of turtles in Nicaragua, an unknown number of green 
turtles and their eggs are also annually harvested throughout the greater Caribbean 
(Bacon 1975; Carr et al. 1982; Bacon et al. 1983; Meylan 1983; Pritchard and Trebbau 
1984; Berry 1989; Eckert and Honebrink 1992; Eckert et al. 1992; Fuller et al. 1992; 
Rueda-Almonacid et al. 1992; Sybesma 1992; Scott and Horrocks 1993). Current annual 
regional harvest levels are unknown, but in Costa Rica alone the annual legal quota of 
green turtles has been 1,800 animals since 1983 (Ogren 1989; WWF 1997). An 
additional 1 ,780 females were estimated to be illegally harvested from the nesting beach 
at Tortuguero in 1997 (Troeng 1997). Because populations are highly migratory the 



154 
activities in one nation can adversely affect the resources of others. The additional 
harvests of green turtles throughout the Caribbean must be considered when assessing the 
impact of the Nicaragua green turtle fishery. Although the Nicaragua fishery is probably 
the largest in the region, this study only provides a partial view of the full magnitude of 
marine turtle exploitation that occurs in the Caribbean. 

My data do not indicate conclusively that the Nicaragua green turtle foraging 
population is overharvested. However, based on the magnitude of the Miskitu Indian 
marine turtle fishery, as well as, the focus of the fishery on large juveniles and adults, 
there is clearly cause for concern. If current harvest levels are not sustainable, population 
declines probably will not be immediately apparent because of the species life history 
traits and fluctuations in harvest pressure. Animals with delayed sexual maturity have 
populations comprising a large percentage of animals in the juvenile stages which 
provides a temporary buffer against extinction (Bjorndal 1985). Fluctuations in harvest 
pressure can allow the population some level of recovery which would also make it 
unlikely that overharvest would be immediately apparent. 
Historical events andJheir effecixjnJhejslatLvejbundance of green turtleJife stages 

Local, regional, and international events can affect exploitation pressure on 
natural resources. International and local demand for green turtles for the past 500 years, 
has greatly affected population levels in the Caribbean (Carr 1954; Parsons 1962; 
Bjorndal 1980b, 1985; Bowen and Avise 1995; Jackson 1997). Bowen and Avise (1995) 
estimated a 99% decline in the Caribbean green turtle population since the late 1400s 
from an estimated 50 million adults, although the basis for their estimate is not given. 



155 
Jackson (1997) estimated the pre-Columbian adult green turtle population in the 
Caribbean at 600 million. Although estimates of the size of the pre-Columbian green 
turtle population in the Caribbean differ, clearly their numbers have declined drastically. 
Green turtle population declines in Bermuda, the Bahamas, the Cayman Islands, Jamaica, 
and various other localities throughout the greater Caribbean have been well documented 
(Lewis 1940; Carr 1954; Parsons 1962; King 1982; Dr. Archie Carr (interview) 1984). In 
order to avoid the shifting baseline syndrome (Pauly 1995; Sheppard 1995), the current 
harvest of green turtles from the Nicaragua foraging ground must be viewed from the 
perspective of an already depleted resource. The shifting baseline syndrome occurs when 
each new generation of scientists accepts the size of a population or species composition 
in an area at the start of their careers as the baseline and all subsequent evaluations are 
based on this starting point. If population size declines or species composition changes 
before the next generation of scientists begin their careers then the result is a gradual shift 
in the baseline and an assessment of species status using inappropriate reference points. 
The following scenario is presented to explain what impact events in the 1900s 
have had on the relative abundance of four green turtle life stages and to explain the 
apparently large numbers of animals available to the Nicaragua fishery today. These life 
stages are: egg/hatchling; small juvenile; large juvenile; and adult. The relative 
abundance of each life stage is categorized qualitatively as "few", "some", "many", and 
"lots". By the turn of the 20th century, green turtle populations in the Caribbean had 
already been depleted by harvesting (Carr 1954; Parsons 1962; King 1982). Regional 
events since the beginning of the 1900s have resulted in variable exploitation pressure on 



156 
Nicaragua's green turtle foraging population affecting the relative abundance of animals 
in each life stage. Below I describe the probable effects these regional events might have 
had on the relative abundance of animals beginning in the 1900s when harvest levels are 
better documented. 

From the early 1900s to 1968, approximately 2,000 to 4,000 green turtles were 
harvested annually from Nicaraguan waters and exported by Cayman turtlers (Ingle and 
Smith 1949; Parsons 1962) . In addition, an unknown quantity of turtles were harvested 
by Miskitu Indians and consumed locally. Although not well documented, total annual 
harvest levels in Nicaragua probably did not exceed 5,000 animals. Harvest at the 
Tortuguero, Costa Rica rookery, during the latter part of this 1900 to 1968 time period, 
included eggs, an estimated one-third of all females that emerged on to the beach, and an 
undetermined number of both males and females from nearshore waters adjacent to the 
nesting beach (Carr 1954, 1969; Carr et al. 1978). Estimates of harvest levels from the 
Tortuguero rookery from 1900 to 1968 are not available. Because juvenile and adult life 
stages are long (i.e, 20 to 50 yrs for juveniles and at least 30 yrs for adults) compared to 
the egg/hatchling stage (i.e., 60 days to 1 yr), animals accumulate in the juvenile and 
adult life stages. Because adults were probably the focus of the fishery and exploitation 
levels relatively low and variable between 1900 and 1968, the relative abundance of each 
life stage by 1968 was probably "some" production in the egg/hatchling, "some" small 
and "many" large juveniles, and "some" adults (Figure 5.1). The relative abundance of 
large juveniles would decline more slowly than the other stages because of continued but 
variable recruitment from the previous stage. 




39VIS 3JH 



158 
In early 1969, the first of three marine turtle processing plants on Nicaragua's 
coast began operations. From 1969 to 1976, an estimated 6,000 to 15,000 or more green 
turtles were harvested annually from the western Caribbean (Nietschmann 1973, 1979b; 
Carr et al. 1978). Due to the increase in exploitation during this period, by the end of the 
period, the relative abundance of the adult life stage probably had declined to a "few" 
animals and as a result there would be relatively "few" egg/hatchlings produced. Because 
small juveniles were not targeted in the fishery their relative abundance would have 
probably remained at "some" animals. Due to the increased demand for turtles during 
this period and declining abundance in the adult stage, harvest pressure probably 
increased in the large juvenile stage as reflected in fewer adults captured (Nietschmann 
1972, 1973, 1976). Thus, the relative abundance in the large juvenile stage would have 
declined to "some" (Figure 5.1). 

Events that occurred during the next period, 1975-1990, afforded animals and 
eggs at the Tortuguero rookery and animals at the Nicaragua foraging ground some 
degree of protection. By the mid-1970s, the beach at Tortuguero was declared a national 
park. By 1 977, all turtle processing plants were closed in Nicaragua and the country 
became a signatory of CITES (Convention on International Trade in Endangered Species 
of Wild Fauna and Flora; Hemley 1994). In the 1980s, Nicaragua was involved in a 
decade-long civil war. Key informants from both the RAAN and RAAS reported a 
decrease in turtling activity during the war. The occurrence of these events from 1975 to 
1990 would have decreased harvest pressure on all life stages, so that by the end of the 



159 
period all life stages would have had approximately 1 5 years to increase, thus, resulting 
in a pulse of animals into the population at all life stages (Figure 5.1). 

Since the end of the war, harvest pressure has increased to current levels of 
approximately 10,000 - 1 1,000 animals/yr. Although results from evaluating the impact 
of the fishery on the foraging population during the 1990s are inconclusive there is a risk 
of evoking the shifting baseline syndrome due to a lack of quantitative data prior to this 
study and its short duration. However, based on the data obtained during this study, there 
is little evidence to indicate that the relative abundance of animals has declined in any of 
the life stages since 1990, the end of the civil-war (Figure 5.1). 

Although the Caribbean green turtle population is still greatly reduced since pre- 
Columbian times, the increase in the abundance of animals from the mid-1970s to 1990 
was apparently sufficient to enable the harvest to reach current levels. If demand 
continues, harvest levels will probably remain high for several more years as small 
juveniles in the "pipeline" move into the harvested size class. The relative abundance of 
the adult stage will decrease more rapidly than the large juvenile stage because large 
juveniles are also harvested in the fishery and thus recruitment into the adult stage will 
decrease. In contrast, recruitment into the large juvenile stage will continue for a longer 
period than into the adult stage because small juveniles are generally not harvested in the 
fishery (Figure 5.1). If current annual harvest levels of large juveniles and adults are 
greater than annual recruitment into these life stages, then eventually the fishery will 
show signs of a declining population by a decrease in CPUE or in the size of animals 
harvested. 



160 
HawkshilLTurlles 

Historical information indicates that hawksbill populations are severely depleted 
in Nicaragua (Nietschmann 1981) and throughout the greater Caribbean region (Parsons 
1972; King 1982; Bjorndal et al. 1993; Meylan 1997a). Severely depleted (small) 
populations are more vulnerable to extinction primarily from environmental and 
demographic stochastic effects (Caughley and Sinclair 1994; Caughley and Gunn 1996) 
and thus these populations should not be harvested. 

Conclusions 

My data do not show conclusively whether or not the current harvest level of 
green turtles is sustainable. Nor do they indicate how many animals of each size class 
and sex can be sustainably harvested. However, there is strong evidence that the life 
stages (juvenile and adult) that affect population change the most (Crouse et al. 1987; 
Congdon et al. 1993, 1994; Congdon and Dunham 1994; Crowder et al. 1994; Heppell et 
al. 1995; Heppell et al. 1996a, b) are most heavily impacted by the fishery. There are 
also some signs of overharvesting (this study). Because the larger (i.e., older) animals are 
targeted, the population will be slow to recover from a decline, if overharvesting is 
occurring. Therefore, managing the fishery is critical. Clearly, more data are needed to 
assess the magnitude of the Nicaragua Caribbean fishery and to thoroughly evaluate its 
impact on populations of green, hawksbill, and loggerhead turtles. The Miskitu Indian 
marine turtle fishery should continue to be monitored and future efforts to characterize 
the populations and model population dynamics are needed to assess the effects of 



161 
different harvest levels. This information will help ensure the long-term survival of these 

endangered species, both as an important cultural and economic resource to coastal 

inhabitants of Nicaragua and as a valuable natural resource to people throughout the 

greater Caribbean (see Chapter 6 for recommendations). 



CHAPTER 6 

MANAGEMENT IMPLICATIONS, 

RECOMMENDATIONS, AND RESEARCH NEEDS 



lionsJoxManaging the Marine_TuudleJEishery 

Today, marine turtles are still an important resource to coastal inhabitants of 
Caribbean Nicaragua. Turtles are an inexpensive source of meat and a source of income 
with which to purchase other goods and services. As with most biological resources, 
however, marine turtle populations can not withstand unlimited exploitation levels. 
Results from this study suggest that current harvest patterns could be exceeding the 
ability of marine turtle populations to maintain themselves. Indications of overharvest 
are the decrease in mean size and weight of harvested green turtles (Chelonia mydas) and 
a decrease in mesh size used in turtlers' nets. In addition, modeling of long-lived, slow- 
maturing iteroparous species, such as sea turtles, has demonstrated that the juvenile and 
adult life stages are the most sensitive to population growth or decline. Thus, the fact that 
the Nicaragua marine turtle fishery targets large juveniles and adults is cause for concern. 

There is a need to regulate the number, size, and sex of animals harvested. 
Because sea turtles are long-lived and slow to reach sexual maturity, low survival in the 
early life stages limits their ability to respond to increased mortality in later life stages 
(Congdon et al. 1993, 1994; Congdon and Dunham 1994), which adds to the challenge of 

162 



163 
managing resource use. As with any species, overexploitation can only be avoided if 
harvest rates do not exceed recruitment rates into the portion of the population harvested. 
Because sea turtle life history traits restrict their ability to respond to persistent and high 
levels of overharvest, humans must control and carefully manage their patterns of 
exploitation. 

Nutritional and economic needs and desires of coastal inhabitants should be met 
with a variety of locally available resources and economic opportunities. The economic 
base of people living on the Caribbean coast of Nicaragua, however, needs to be 
broadened by developing alternative economic resources to mitigate pressure on sea 
turtles. Unless properly managed, the Miskitu Indian marine turtle fishery is likely to 
negatively impact sea turtle populations throughout the greater Caribbean, and eventually 
affect the availability of marine turtles as a resource for future generations of Miskitu 
Indians. 

Governmental institutions usually are mandated to establish policies for natural 
resource use, develop management plans, and enforce laws that govern resource use. 
However, governmental institutions are often not able, neither financially, technically, or 
politically, to manage and enforce natural resource use. For these reasons, governmental 
institutions must involve local resource users in the decision-making process and 
implementation of managing resource use (Bromley and Cernea 1989; Rettig et al. 1989; 
Ostrom 1990; Pomeroy 1995; Harrington and Gallucci 1996; Jain 1996; Stocks 1996). In 
Nicaragua, the government institution, Ministerio del Ambiente y Recursos Naturales 
(MARENA), mandated to manage natural resources in the country is constrained by 



164 
insufficient finances, lack of technical expertise, and little political influence on the 
Caribbean coast. In addition, they are also separated geographically and culturally from 
marine turtle harvesters and consumers on that coast. Thus, the marine turtle fishery 
needs to be co-managed by all the stakeholders of this resource, which includes but is not 
limited to the turtling communities, marine turtle butchers, MARENA, regional 
autonomous governments (RAAN and RAAS), coastal municipalities, navy, and 
nongovernmental organizations (NGO). Involving resource users and other interest 
groups in co-management of resource exploitation improves the chances of successfully 
achieving a sustainable harvest and enforcing regulations to conserve the resource 
(Pomeroy 1995; Harrington and Gallucci 1996; Jain 1996; also see Pinkerton 1989 for 
examples of various co-management schemes). One major difference between the 
Nicaragua marine turtle fishery and other fisheries is that in Nicaragua there is only one 
user group (coastal indigenous people), and therefore, no competition for the resource 
occurs between the different stakeholders as with most other fisheries. Thus, co- 
management of the marine turtle fishery in Nicaragua is needed to regulate the fishery for 
the sustainable use of the resource, but not to regulate resource allocation, and spatial or 
temporal access to the resource among user groups. 

In Nicaragua, establishing collaborative agreements among the various 
stakeholders on the Caribbean coast will be particularly challenging because of past 
events. One result from the negotiations to end the Nicaragua civil war of the 1980s was 
an agreement by the central government to grant autonomy to the people living in the 
eastern Caribbean lowlands of the country. Two regional autonomous governments (one 



165 
in the north and one in the south) were established to govern regional issues, including 
the use and management of natural resources. In addition, by legislative decree, the 
inhabitants of the Caribbean lowlands were given the right to use and enjoy the natural 
resources of the autonomous regions (D. Castro pers. com.). This clearly presents a 
conflict between the establishment of regulations by the central government and resource 
users of the autonomous regions. 

Another event was the establishment of the Reserva de Biosfera de las 
Comunidades Indigenas y Cayos Miskitos (Indigenous Communities and Miskito Cays 
Biosphere Reserve ) in 1991. Impetus for the reserve was the concern for overuse of and 
competition for the natural resources in the region. The reserve encompasses 24,000 km 2 
in the RAAN, including 38 indigenous communities, and offshore cays and reefs (Equipo 
Tecnico de Planificacion 1995). A draft management plan for the reserve has been 
written based on the concerns of the indigenous communities for competition with non- 
Miskitu groups for natural resources (D. Castro pers. com.). However, it does not include 
the management of the marine turtle fishery because, again, there is no competition from 
non-Miskitu interests for the harvest of marine turtles. There is still no formal 
institutional structure for management of the reserve, and as a result, development of the 
reserve and activities are essentially paralyzed (Jain 1996). Although marine turtles were 
not considered in the draft management plan for the reserve, an important outcome in the 
process of writing the draft plan was the inclusion of the indigenous communities. In 
addition, the fact that the communities do not compete with other interest groups for 



166 
marine turtles makes the issue less political and places the responsibility of managing the 
turtle harvest squarely in their hands. 

The people that most directly depend on the resource will either prosper in the 
long-term when exploitation levels are managed within biological limits of the resource 
or suffer the consequences when the resource is overharvested and no longer available for 
human use. Therefore, the ultimate burden of maintaining a sustainable marine turtle 
harvest lies with the people that depend on the resource and are the direct beneficiaries of 
sound resource use. This is not to imply that government institutions, NGOs, and the 
scientific community do not have a role to play in assisting resource users to develop 
more sustainable resource use practices. Through associations with conservation 
organizations and government institutions, resource users should be supported and 
assisted in the development of alternative resources and economic options, provided with 
knowledge and information about the resource, and assisted in obtaining data to make the 
most informed management decisions (Stocks 1996). Although, approaches to 
developing collaborative agreements with local resource users and finding solutions to 
conservation issues can sometimes be transferred among geographic locations, human use 
patterns of natural resources are often site specific and biological constraints are species 
specific and often require unique solutions to conservation issues. 

The conservation and management of the marine turtle fishery on the Caribbean 
coast of Nicaragua needs to begin within the turtling communities. It is absolutely 
imperative that the Miskitu people, as a community, be actively involved in the decision 
making process of establishing the rules and regulations needed to manage this fishery for 



167 
a more sustained harvest. Although community members are the harvesters of marine 
turtles and the beneficiaries of the resource, they are the preferred stewards because they 
have the most to lose if the resource declines. Since currently no marine turtle fishery 
management plan exists, it is important that the turtling communities agree to establish 
regulations that will, at the very least, prevent the harvest from increasing. 
Simultaneously, education and training programs should be implemented to provide 
coastal inhabitants with biological knowledge about the species and training in collecting 
and analyzing biological data on the turtles, as well as, sociological and economic data 
about the marine turtle fishery. 

Because the cost of marine turtle meat is currently the second, only to fish, least 
expensive source of protein on the Caribbean coast, alternative sources of inexpensive 
protein need to be explored and additional economic opportunities developed. In 
exchange, turtlers will need to agree to restrict their harvest of marine turtles. Below I 
have listed the most immediate management actions that I recommend be considered, 
modified if necessary, and implemented by the turtling communities. The section on 
management recommendations is followed by a section on research needs. I list the most 
important research needs that will provide us with the additional information needed to 
better manage the marine turtle fishery for the long-term survival of turtle populations. 

M anagement E^cojamendations 

The following recommendations are made with the limited data available and will 
need revision when data on the turtle populations in the region have been obtained. 



168 
Regulations that impinge on social, economic, and cultural aspects of the turtlers, turtle 
butchers, and coastal inhabitants will need to be discussed and agreed on among the 
various interest groups. 

1 . Continue monitoring the marine turtle harvest through local community data 
collectors. For each turtling trip at least the following information should be 
recorded: turtler's community of residence, trip dates, number of days turtling, 
capture location(s), harvest method, number of nets (if used), number of turtlers, 
number of turtles captured by species, and size and sex of animals captured. 

2. Expand monitoring of the harvest to include the communities of Rama Indians that 
harvest turtles, as well as, the additional three Miskitu Indian communities in the 
RAAN. 

3. Establish monthly harvest quotas for each turtling community based on current 
harvest rates to prevent the total annual harvest of green turtles from exceeding 
10,000 animals. This could be accomplished by monitoring monthly harvest rates 
for each community and adjusting harvest levels in subsequent months. 

4. Establish restrictions on the harvest of green turtles to lessen the impact of the 
harvest on the population. Because insufficient data are available to determine 
which life stage (i.e., juveniles or adults) should be protected to maximize population 
growth rates, the following discussion of advantages and disadvantages of various 
strategies is provided. However, for any strategy to be effective, it is imperative that 
the Caribbean Nicaragua turtlers are included in discussions about restricting the 
harvest and deciding which restrictions to adopt. 



169 

a. Decrease the number of female adult and large juvenile green turtles 
harvested. Even though the sex ratio indicates that more females occur in the 
foraging population, females are more valuable for population growth and, 
therefore are important to obtaining the highest population growth rate. 

b. Establish a closed season on the harvest of females > 88.0 cm carapace length 
(CL) from January through May to allow the migration of reproductively 
active females of the year to migrate to the nesting beaches. However, partial 
year-around closed seasons for specific sexes or size classes are less protective 
and difficult to enforce. They are also potentially confusing and are more 
easily misinterpreted. 

c. Protect male and female green turtles < 88.0 cm CL throughout the year. The 
presence of corpora lutea indicates that approximately 50% of females > 88.0 
cm CL are reproductively mature (see Figure 4.5B). The protection of 
animals < 88.0 cm CL will allow some animals to reach sexual maturity and 
reproduce. Based on modeling studies of long-lived, iteroparous species 
increased survival in the juvenile life stage results in the highest population 
growth rate. If only immature animals are protected, however, the increased 
harvest pressure on mature animals could result in fewer reproductive 
individuals in the population. 

d. Protect male and female green turtles > 88.0 cm CL throughout the year. This 
would provide protection to the majority of animals that have already reached 
sexual maturity. If only mature animals are protected, however, the increased 



170 
harvest pressure on juvenile animals could eventually result in a smaller adult 
population because fewer juveniles would recruit into the adult stage to 
replace adults lost to reproductive senescence and mortality outside the 
Nicaragua turtle fishery. 

6. Prohibit the transportation of green turtles to the Rio Coco region (located on the 
border with Honduras) and to interior savannah communities. Consumption of turtle 
meat in these areas is not yet an established custom and should be discouraged to 
contain the market for sea turtle products. 

7. Prohibit the sale and use of any marine turtle species for bait in other fisheries. 

8. Establish a minimum mesh size of 16 in (41 cm) bar for turtle entanglement nets. 

9. Establish a country- wide ban on the harvest, use, and sale of hawksbill 
(Eretmochelys imbricata) meat, eggs, and tortoiseshell. 

10. Promote the live release of loggerheads (Caretta caretta) and leatherbacks 
(Dermochelys coriacea) when they are captured. 

1 1 . Promote the cultivation and consumption of alternative, inexpensive sources of 
animal protein to be bred and sold by turtlers to substitute lost income from the sale 
of marine turtles. Alternative meat sources will need to be evaluated for cultural 
acceptance and economic viability. 

12. Develop and promote additional economic opportunities, such as, tourism, the sale 
of goods produced by the woman's sewing club, animal husbandry, and the 
production and sale of fruit currently produced in the communities. 



171 

13. Develop alternative economic opportunities for the turtle butchers in Puerto Cabezas 
to decrease their dependence on marine turtles for income. 

14. Identify and establish marine turtle capture sites to be used for long-term monitoring 
of population trends. 

15. Develop alternative sources of material, instead of coral, to use in the footline of 
turtle nets and encourage turtlers to reuse already harvested coral. Encourage the use 
of dead coral that has been washed-up during storms and litters many beaches and 
shoreline areas. 

16. Establish and enforce a law that requires the use of Turtle Excluder Devices (TEDs) 
on all shrimp trawlers to decrease the drowning or additional harvest of turtles in 
shrimp nets. 

Recommendations for Future Resear ch 

1 . Conduct in-water studies to characterize the foraging populations. Studies should 
include the following components: 

a) determine relative density, and survival and growth rates of turtles by 
conducting mark/recapture studies, 

b) determine characteristics (i.e., size, sex, and genetic stock) of juvenile 
populations, 

c) determine recruitment rate of turtles into the harvested populations, 

d) determine habitat use by size class and sex and determine available habitat, and 

e) determine migratory patterns to and from nesting beaches. 



172 

2. Determine the proportion of animals in various reproductive states (i.e., immature, 

mature, reproductively active) from a random sample of harvested animals and 
monitor changes over time. 

3. Develop a population projection model to evaluate survival outlook of the foraging 
population based on current harvest levels and population density, and to evaluate 
different management strategies. 

4. Survey hawksbill nesting populations along the southern Caribbean coast of the 
country to determine their status and harvest pressure. 

5 . Characterize the population of loggerheads in Nicaragua' s Caribbean waters. 
Studies would include the following components: 

a) determine size and sex of animals captured in the fishery, 

b) determine relative density of turtles by conducting mark/recapture studies, 

c) determine size, sex, and genetic stock of the in- water population, and 

d) determine if the population on the foraging ground is resident, seasonal, or 
migratory. 

6. Quantify the amount of coral harvested for use in the fishery and investigate impacts 
to coral communities. 



APPENDIX A 
MINIMUM NUMBER AND (PERCENT) OF MARINE TURTLES CAPTURED IN THE 
REGION AUTONOMA DEL ATLANTICO NORTE, NICARAGUA FOR THE PERIODS 
FEBRUARY 1994 TO JANUARY 1995 AND DECEMBER 1995 TO APRIL 1997 







Chelonia mydas 








Eretmochelys imbricala 






Carella 


carella 




Capture 
Location 


AW 


DK" 


SB' 


UNK" 


TOP 


AW 


DK 


SB 


TOT 


AW 


DK 


SB 


TOT 


Awastara 


18 











18 














4 








4 




(0.3) 


(0) 


(0) 


(0) 


(0.2) 


(0) 


(0) 


(0) 


(0) 


(0.7) 


(0) 


(0) 


(0.6) 


Broston Bar 


93 





123 





216 








1 


1 


2 





5 


7 




(1.3) 


(0) 


(4.3) 


(0) 


(1.9) 


(0) 


(0) 


(5.0) 


(1.3) 


(0.4) 


(0) 


(12.2) 


(1.1) 


Buhnitara 


14 








10 


24 














1 








1 




(0.2) 


(0) 


(0) 


(3.8) 


(0.2) 


(0) 


(0) 


(0) 


(0) 


(0.2) 


(0) 


(0) 


(0.2) 


Com Fish 








22 





22 








1 


1 
















(0) 


(0) 


(0.8) 


(0) 


(0.2) 


(0) 


(0) 


(5.0) 


(1.3) 


(0) 


(0) 


(0) 


(0) 


D.D. Rock 


10 


87 








97 





1 





1 
















(0.1) 


(5.4) 


(0) 


(0) 


(0.8) 


(0) 


(4.3) 


(0) 


(1.3) 


(0) 


(0) 


(0) 


(0) 


Deadman 








56 





56 


























Bar 


(0) 


(0) 


(2.0) 


(0) 


(0.5) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


Diamond 


69 


10 


1,157 





1,236 








7 


7 


2 





5 


7 


Patch 


(1.0) 


(0.6) 


(40.7) 


(0) 


(10.6) 


(0) 


(0) 


(35.0) 


(9.0) 


(0.4) 


(0) 


(12.2) 


(1.1) 


Dos Palitos 








28 





28 




























(0) 


(0) 


(10) 


(0) 


(0.2) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


Engine Bar 








104 





104 








1 


1 








2 


2 




(0) 


(0) 


(3.7) 


(0) 


(0.9) 


(0) 


(0) 


(5.0) 


(1.3) 


(0) 


(0) 


(4.9) 


(0.3) 


Franklin 


17 











17 


1 








1 














Reef 


(0.2) 


(0) 


(0) 


(0) 


(0.1) 


(2.9) 


(0) 


(0) 


(1.3) 


(0) 


(0) 


(0) 


(0) 


Inin 








18 





18 




























(0) 


(0) 


(0.6) 


(0) 


(0.2) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


Karil 


48 











48 














4 








4 




(0.7) 


(0) 


(0) 


(0) 


(0.4) 


(0) 


(0) 


(0) 


(0) 


(0.7) 


(0) 


(0) 


(0.6) 


Leimarka 


895 


113 


57 





1,065 


3 


2 





5 


172 


2 





174 




(13.0) 


(7.0) 


(2.0) 


(0) 


(9.2) 


(8.6) 


(8.7) 


(0) 


(6.4) 


(31.9) 


(3.9) 


(0) 


(27.6) 


London Reef 





3 


22 





25 




























(0) 


(0.2) 


(0.8) 


(0) 


(0.2) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


Mackensie 


13 


91 


20 





124 





1 





1 


1 


1 





2 


Bar 


(0.2) 


(5.6) 


(0.7) 


(0) 


(1.1) 


(0) 


(4.3) 


(0) 


(1.3) 


(0.2) 


(2.0) 


(0) 


(0.3) 



173 



174 







Chehnia mydas 








Eretmochelys imbricata 






Caretta c arena 




Capture 
Location 


AW 


DK" 


SB' 


UNK" 


TOP 


AW 


DK 


SB 


TOT 


AW 


DK 


SB 


TOT 


Maras Cay 


206 
(3.0) 


110 
(6.8) 


13 
(0.5) 



(0) 


329 
(2.8) 


1 
(2.9) 


1 
(4.3) 



(0) 


2 
(2.6) 


5 
(0.9) 


4 
(7.8) 


1 

(2.4) 


10 
(1.6) 


Miskito Cay 


324 
(4.7) 


2 
(0.1) 


6 
(0.2) 



(0) 


332 
(2.9) 


4 

(11.4) 



(0) 



(0) 


4 
(5.1) 


35 
(6.5) 



(0) 



(0) 


35 
(5.5) 


Bet. Miskito 
& Maras 


43 
(0.6) 



(0) 


4 
(0.1) 



(0) 


47 
(0.4) 



(0) 



(0) 



(0) 



(0) 


2 
(0.4) 



(0) 


2 
(4.9) 


4 
(0.6) 


Muna de 

Nasa 



(0) 



(0) 


26 
(0.9) 



(0) 


26 
(0.2) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


Nasa Cay 


468 
(6.8) 


106 
(6.6) 


204 
(7.2) 



(0) 


778 
(6.7) 


1 

(2.9) 


1 

(4.3) 


1 

(5.0) 


3 
(3.8) 


48 
(8.9) 



(0) 



(0) 


48 
(7.6) 


Nasa Sautka 



(0) 



(0) 


17 
(0.6) 



(0) 


17 
(0.1) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


1 

(2.4) 


1 
(0.2) 


Ned Thomas 



(0) 


29 
(1.8) 


80 
(2.8) 



(0) 


109 
(0.9) 



(0) 



(0) 



(0) 



(0) 



(0) 


2 
(3.9) 


2 
(4.9) 


4 
(0.6) 


Nee Reef 



(0) 



(0) 


120 
(4.2) 



(0) 


120 
(1.0) 



(0) 



(0) 


2 
(10.0) 


2 
(2.6) 



(0) 



(0) 


7 
(17.1) 


7 
(1.1) 


Oben Sol 



(0) 


15 
(0.9) 



(0) 



(0) 


15 
(0.1) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


Papta 


22 
(0.3) 


12 
(0.7) 



(0) 



(0) 


34 
(0.3) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


Plaik 



(0) 



(0) 


86 
(3.0) 



(0) 


86 
(0.7) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


Pies Raya 


403 
(5.8) 


7 
(0.4) 


95 
(3.3) 



(0) 


505 
(4.3) 


6 
(17.1) 



(0) 



(0) 


6 

(7.7) 


11 

(2.0) 



(0) 


5 
(12.2) 


16 
(2.5) 


Reef 



(0) 



(0) 


87 
(3.1) 



(0) 


87 
(0.7) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


3 
(7.3) 


3 

(0.5) 


Siakualaya 


21 
(0.3) 


65 
(4.0) 



(0) 



(0) 


86 
(0.7) 



(0) 


3 
(13.0) 



(0) 


3 
(3.8) 


1 

(0.2) 


9 
(17.6) 



(0) 


10 
(1.6) 


Sleps 


18 
(0.3) 



(0) 



(0) 



(0) 


18 
(0.2) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


Southeast 
Rock 


24 
(0.3) 



(0) 



(0) 


26 
(9.9) 


50 
(0.4) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


Tistan Reef 



(0) 



(0) 


13 
(0.5) 



(0) 


13 

(0.1) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 



(0) 


Udlock Rock 



(0) 



(0) 


28 
(1.0) 



(0) 


28 
(0.2) 



(0) 



(0) 


1 

(5.0) 


1 

(13) 



(0) 



(0) 


2 
(4.9) 


2 
(0.3) 


Uiplin 


202 
(2.9) 


190 
(11.8) 


72 
(2.5) 



(0) 


464 
(4.0) 


1 

(2.9) 


4 
(17.4) 


1 

(5.0) 


6 

(7.7) 


3 
(0.6) 


11 

(21.6) 


1 
(2.4) 


15 
(2.4) 


Waham 


71 
(1.0) 


146 
(9.0) 



(0) 



(0) 


217 
(1.9) 



(0) 


3 
(13.0) 



(0) 


3 
(3.8) 


2 
(0.4) 


3 
(5.9) 



(0) 


5 
(0.8) 


Waltara 



(0) 


2 
(0.1) 



(0) 



(0) 


2 
(0.02) 



(0) 



(0) 



(0) 



(0) 



(0) 


2 
(3.9) 



(0) 


2 
(0.3) 


White Hole 
Cay 


31 
(0.4) 


176 
(10.9) 


27 
(0.9) 



(0) 


234 
(2.0) 



(0) 


5 
(21.7) 



(0) 


5 
(6.4) 


2 
(0.4) 


7 
(13.7) 



(0) 


9 
(1.4) 



175 



Capture 




Chehnia mydas 








Erelmochelys imbricata 






Carella 


carella 






























Location 


AW 


DK" 


SB' 


LINK" 


TOT* 


AW 


DK 


SB 


TOT 


AW 


DK 


SB 


TOT 


Witties 


3,862 


340 


284 


216 


4,702 


18 





3 


21 


244 


5 


3 


252 




(56.1) 


(21.1) 


(10.0) 


(82.1) 


(40.5) 


(51.4) 


(0) 


(15.0) 


(26.9) 


(45.3) 


(9.8) 


(7.3) 


(39.9) 


Won kluna 











11 


11 




























(0) 


(0) 


(0) 


(4.2) 


(0.1) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


Yankalaya 


18 











18 




























(0.3) 


(0) 


(0) 


(0) 


(0.2) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


(0) 


TOTAL 


6,890 


1,614 


2,844 


263 


11,611 


35 


23 


20 


78 


539 


51 


41 


631 



a AW = Awastara 

b DK = Dakra 

c SB = Sandy Bay 

d UNK = Unknown community 

e TOT = Total for the row by species. 



APPENDIX B 

MINIMUM NUMBER OF MARINE TURTLES CAPTURED BY COMMUNITY 

IN THE REGION AUTONOMA DEL ATLANTICO SUR, NICARAGUA 



Rio Grande Bar (April 1991 to December 1996, for 46 mo of the 69-mo period) 





Chelonia mydas 


Eretmochelys imbricata 


Caretta caretta 


Capture Location 


Number 


Percent 


Number 


Percent 


Number 


Percent 


Big Criki 


110 


2.0 














Big Northeast 


63 


1.1 














Big Shoal 


42 


0.7 














Boor Bila 


49 


0.9 














Brisbane Shoal 


98 


1.7 














De Tronco 


347 


6.2 


2 


16.7 


4 


40.0 


Duban 


423 


7.5 














East 


82 


1.5 


1 


8.3 








East/Northeast 


43 


0.8 


1 


8.3 


1 


10.0 


East/Southeast 


18 


0.3 


1 


8.3 


1 


10.0 


For Now This 


15 


0.3 














Half-way Bank 


1,164 


20.7 


3 


25.0 


1 


10.0 


Jaco Shoal 


135 


2.4 














Jorge Hall 


32 


0.6 














Karmutra Bank 


787 


14.0 


1 


8.3 


1 


10.0 


Kuala Cay 


45 


0.8 














Northeast 


260 


4.6 


1 


8.3 


2 


20.0 


North/Northeast 


353 


6.3 


2 


16.7 








Northwest 


4 


0.1 















176 



177 





Chelonia mydas 


Eretmochelys imbricata 


Caretta caretta 


Capture Location 


Number 


Percent 


Number 


Percent 


Number 


Percent 


Southeast 


228 


4.1 














Vietnam Bank 


1,076 


19.1 














Vietnam Sur 


30 


0.5 














Washer Woman 


195 


3.5 














Yankee Shoal 


25 


0.4 














TOTAL 


5,624 


100.1 


12 


99.9 


10 


100 



Data for 1991 to 1993 were provided by the Centro de Investigaciones y Documentation de la Costa 
Atlantica. 



Sandy Bay Sirpi (January 1991 to December 1996, for 64 mo of the 72-mo period) 





Chelonia mydas 


Eretmochelys imbricata 


Caretta caretta 


Capture Location 


Number 


Percent 


Number 


Percent 


Number 


Percent 


Alge Bank 


9 


0.2 














Auhya Pihni 


376 


7.6 


1 


2.8 








Big Shoal 


39 


0.8 














Buhni Pahni 


125 


2.5 








1 


3.6 


Clar Cay 


198 


4.0 


1 


2.8 








Devil Hole 


315 


6.4 








1 


3.6 


Diamond Spot 


145 


2.9 








6 


21.4 


Diapapa Bank 


4 


0.1 














Dos Hermanos 


28 


0.6 














Family Shoal 


392 


7.9 


2 


5.6 


12 


42.9 


Half-way Bank 


470 


9.5 


6 


16.7 








Hawksbill Bank 


141 


2.9 


14 


38.9 








Jim Time 


156 


3.2 


1 


2.8 


1 


3.6 


Kiski Tara 


30 


0.6 














Liwa Pin 


90 


1.8 















178 





Chelonia mydas 


Eretmochelys imbricata 


Caretta caretta 


Capture Location 


Number 


Percent 


Number 


Percent 


Number 


Percent 


Lousigsa 


133 


2.7 


6 


16.7 


3 


10.7 


Mabra Pin Lalma 


49 


1.0 














Man O' War Cay 


128 


2.6 














Man 0' War Lalma 


17 


0.3 


o 











Man 0' War 


43 


0.9 














Waupasa 














Masmaslaya 


71 


1.4 














Nicro Sal Bank 


41 


0.8 


1 


2.8 








North Schooner 


108 


2.2 














Rolan Tara 


31 


0.6 














Salikan Bila 


6 


0.1 














Sandy Bay Sirpi 


25 


0.5 














Skuna Yahbraro 


13 


0.3 














Snukrik 


13 


0.3 














South Schooner 


606 


12.3 














Tingni Tara 


108 


2.2 














Wainwin 


633 


12.8 


4 


11.1 


1 


3.6 


Wainwin Munnita 


17 


0.3 














Wainwin Waupasa 


6 


0.1 














Wanklua 


350 


7.1 








3 


10.7 


TOTAL 


4,937 


99.9 


36 


100.2 


28 


100.1 



Data for 1991 to 1993 were provided by the Centro de Investigaciones y Documentaci6n de la Costa 
Atlantica. 



179 



Set Net (July 1994 to December 1996, 30 mo) 





Chelonia mydas 


Eretmochelys 


imbricata 


Caretta caretta 


Capture Location 


Number 


Percent 


Number 


Percent 


Number 


Percent 


Columbilla Cay 


9 


1.2 














Compass 


61 


8.0 


2 


11.1 


1 


5.0 


Crowning Spot 


22 


2.9 


1 


5.6 








Fowlshit Bank 


488 


64.2 


4 


22.2 


9 


45.0 


Long Reef 


149 


19.6 


9 


50.0 


10 


50.0 


Maroon Cay 


22 


2.9 


2 


11.1 








North Long Reef 


9 


1.2 














TOTAL 


760 


100 


18 


100 


20 


100 



Tasbapaune (November 1993 to December 1996, for 36 mo of the 38-mo period) 





Chelonia 


mydas 


Eretmochelys imbricata 


Caretta caretta 


Capture Location 


Number 


Percent 


Number 


Percent 


Number 


Percent 


Au Dakra 


12 


0.2 














Buscan 


902 


14.7 


12 


17.6 


17 


23.9 


Cama Cay 


26 


0.4 


1 


1.5 


1 


1.4 


Columbilla Cay 


10 


0.2 














Haulover 


1,525 


24.9 


20 


29.4 








Joe Bush 


131 


2.1 








1 


1.4 


Kiama Cay 


22 


0.4 














Kings Cay 


98 


1.6 


1 


1.5 


1 


1.4 


Karaslaya 


33 


0.5 














Kingsman Bank 


426 


6.9 


5 


7.4 








Middle Bank 


815 


13.3 


8 


11.8 


23 


32.4 


Prata Shoal 


489 


8.0 


4 


5.9 


22 


31.0 



180 





Location 


Chelonia mydas 


Eretmochelys 


imbricata 


Caretta caretta 


Capture 


Number 


Percent 


Number 


Percent 


Number 


Percent 


Patan 
Rivas 




496 
1,150 


8.1 
18.7 


6 
11 


8.8 
16.2 



6 



8.5 


TOTAL 




6,135 


100 


68 


100.1 


71 


100 



APPENDIX C 

MINIMUM NUMBER OF GREEN TURTLES, CHELON1A MYDAS, LANDED AT 

EACH SITE ON THE CARIBBEAN COAST OF NICARAGUA FROM 1991 TO 1996 






182 



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APPENDIX D 

PEARSON CORRELATION COEFFICIENTS FOR TEN 

BODY MEASUREMENTS OF GREEN TURTLES, CHELONIA MYDAS, 

HARVESTED FROM THE CARIBBEAN WATERS OF NICARAGUA 



185 



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— 



APPENDIX E 

REGRESSION ANALYSIS OF CURVED CARAPACE LENGTH (CLN) AGAINST NINE 

OTHER BODY MEASUREMENTS OF HARVESTED GREEN TURTLES, CHELONIA 

MYDAS, BY SEX FROM THE CARIBBEAN WATERS OF NICARAGUA 



Test for significant difference of regression by sex 




Simple linear regression equation 


X 


Y 


F 

Interc. 
Slope 


DF 


n 

¥ 


P= 
Interc. 
Slope 




a 


b 


n 


r 2 


F 


DF 


P< 




For pooled sexes 


CLN 


SLT 


0.95 
2.79 


3,489 


245 
248 


0.33 
0.096 




1.31 


0.95 


529 


0.98 


27494 


1,527 


0.0001 


CLN 


log PL 


0.06 
0.01 


3,543 


276 
271 


0.81 
0.91 




3.38 


0.0097 


598 


0.86 


3726 


1,596 


0.0001 


CLN 


logWT 


0.07 
0.16 


3,545 


276 
273 


0.79 
0.69 




1.30 


0.034 


596 


0.92 


6859 


1,594 


0.0001 




For separate sexes 


CLN 


CLT 


10.98 
11.23 


3,487 


245 
246 


0.0010 
0.0009 


? 


0.27 


1.02 


245 


0.99 


30031 


1,243 


0.0001 


<y 


3.07 


0.99 


246 


0.99 


21066 


1,244 


0.0001 


CLN 


SLN 


8.38 
14.28 


3,554 


276 
282 


0.0039 
0.0002 


¥ 


-0.48 


0.95 


276 


0.99 


31783 


1,274 


0.0001 


<f 


-2.78 


0.98 


282 


0.99 


21376 


1,280 


0.0001 


CLN 


log 
VENT 


83.71 
150.60 


3,530 


272 
262 


0.0001 
0.0001 


¥ 


0.53 


0.023 


272 


0.66 


536 


1,270 


0.0001 


a 


-1.21 


0.048 


262 


0.68 


624 


1,260 


0.0001 


CLN 


log TAIL 


91.28 
166.64 


3,542 


274 

272 


0.0001 
0.0001 


¥ 


0.90 


0.023 


274 


0.75 


840 


1,272 


0.0001 


cC 


-0.76 


0.047 


272 


0.69 


656 


1,270 


0.0001 


CLN 


log 
xCBASE 


71.65 

127.75 


3,510 


253 
261 


0.0001 
0.0001 


? 


-0.44 


0.027 


253 


0.66 


501 


1,251 


0.0001 


o" 


-2.48 


0.056 


261 


0.62 


533 


1,259 


0.0001 


CLN 


log 
xCLEN 


75.31 
135.79 


3,503 


250 

257 


0.0001 
0.0001 


¥ 


-1.23 


0.014 


250 


0.23 


76 


1,248 


0.0001 


«f 


-3.53 


0.048 


257 


0.56 


391 


1,255 


0.0001 



Table adapted from Limpus et al. 1994a. Turtles were landed at Puerto Cabezas, Nicaragua from November 1993 to January 1995. Male 
and female measurements were pooled when there was no significant difference in the slope and intercept between the sexes. 
CLN = minimum (notch-to-notch) curved carapace length, SLN = minimum (notch-to-notch) straight carapace length, CLT = maximum (tip- 
to-tip) curved carapace length, SLT ■ maximum (tip-to-tip) straight carapace length, PL = plastron length, VENT = plastron to vent length, 
TAIL = tail length, xCBASE = mean basal area of anterior claw/turtle, xCLEN = mean anterior claw length/turtle, and WT = body mass. 



186 



APPENDIX F 

MINIMUM NUMBER OF HAWKSBILL, ERETMOCHELYS IMBRICATA; 

LOGGERHEAD, CARETTA CARETTA; AND LEATHERBACK, DERMOCHELYS 

CORIACEA, TURTLES REPORTED CAPTURED AND/OR HARVESTED IN THE 

CARIBBEAN WATERS OF NICARAGUA FROM 1991 TO 1996 



Regi6n 

Aut6noma 

del 

Atlantico 

Norte 


Eretmochelys imbricata 


Caretta caretta 


Dermochelys coriacea 


RECORDED 


REC 


EST 
TOT 


RECORDED 


RECORDED 


1991 a 


1992 a 


1993 a 


1994 


1995 


1996 


1994 


1995 


1996 


1994 


1995 


1996 


Awastara 


N/A 


N/A 


4 


25 


14 


6 


33 
(4) 


99 b 


92 


327 











Dakra 


N/A 


N/A 


N/A 


14 


1 


11 


8 
(4) 


24 b 


7 


34 





3 





Sandy Bay 


N/A 


N/A 


N/A 


22 


9 


12 


15 
(4) 


45 b 


27 


21 











Other' 


N/A 


N/A 


2 


13 


3 





1 


1 


6 


3 











Subtotal 


N/A 


N/A 


6 


74 


27 


29 


57 


169 b 


132 


385 





3 





Regi6n 
Aut6noma del 
Atlantico Sur 


Rio Grande 
Bar 


N/A 


1 


N/A 


2 


3 


6 


3 


3 


7 


8 











Sandy Bay 
Sirpi 


3 


1 


13 


5 


10 


5 


N/A 


N/A 


11 


18 











Set Net 


N/A 


N/A 


N/A 


2 


12 


4 


1 


1 


10 


9 











Tasbapaune 


N/A 


N/A 


N/A 


3 


57 


9 








9 


63 





1 





Subtotal 


3 


2 


13 


12 


82 


24 


4 


4 


37 


98 





1 





TOTAL 


3 


2 


19 


86 


109 


53 


61 


173 b 


169 


483 





4 






Numbers in parentheses are months. 

REC = Recorded, EST TOT - Estimated Total, N/A = No data are available. 

a Data for 1991 - 1993 were provided by the Centra de Investigaciones y Documentacidn de la Costa Atlantica. 

b Data is based on the mean number of turtles landed per month for months in which data were recorded for that year. 

c Includes the communities of Krukira and Pahra and mechanized fishing boats. 



187 






APPENDIX G 

SUMMARY STATISTICS OF BODY SIZE PARAMETERS FOR 

HARVESTED HAWKSBILL, ERETMOCHELYS IMBRICATA, TURTLES 



Body 




Female 




Male 




Combined 




Measurements 
(cm) 


Mean 
(SD) 


Range 


n 


Mean n 
(SD) 


Mean 
(SD) 


Range 


n 


CLN 


77.8 
(7.4) 


67.0-85.6 


5 


73.7 1 


77.2 
(6.8) 


67.0-85.6 


6 


SLN 


73.8 
(5.1) 


68.2-78.2 


3 




73.8 
(5.1) 


68.2-78.2 


3 


CLT 


84.9 
(5.4) 


77.6-90.5 


4 




84.9 
(5.4) 


77.6-90.5 


4 


SLT 


78.4 
(5.6) 


72.5-83.7 


3 




78.4 
(5.6) 


72.5-83.7 


3 


PL 


59.1 
(4.3) 


54.1-63.5 


5 


53.4 1 


58.2 
(4.5) 


53.4-63.5 


6 


VENT 


12.5 
(1.8) 


11.5-15.7 


5 


14.6 1 


12.9 
(1.8) 


11.5-15.7 


6 


TAIL 


17.3 
(2.2) 


15.2-20.9 


5 


18.6 1 


17.5 
(2.0) 


15.2-20.9 


6 


xCBASE 


6.0 
(0.5) 


5.6-6.4 


2 




6.0 
(0.5) 


5.6-6.4 


2 


xCLEN 


1.4 
(0.2) 


1.3-1.6 


2 




1.4 
(0.2) 


1.3-1.6 


2 


WT (kg) 


53.3 
(13.0) 


45.4-72.6 


4 




53.3 
(13.0) 


45.4-72.6 


4 



CLN = minimum (notch-to-notch) curved carapace length, SLN = minimum (notch-to-notch) straight 
carapace length, CLT = maximum (tip-to-tip) curved carapace length, SLT = maximum (tip-to-tip) straight 
carapace length, PL = plastron length, VENT = plastron to vent length, TAIL = tail length, xCBASE = 
mean basal area of anterior claw/turtle, xCLEN = mean anterior claw length/turtle, and WT = body mass. 
See text for a detailed description of measurements. 



188 



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BIOGRAPHICAL SKETCH 

Cynthia Jean Lagueux was born in Minneapolis, Minnesota, on 20 July 1954. At 
an early age she was exposed to many cultures, customs, and languages. During her pre- 
school years she and her family lived in Burma (now Myanmar) for three and one-half 
years. During this period they had the opportunity to travel around the world twice 
visiting many countries. In 1972, Ms Lagueux graduated from Edison high school in 
Minneapolis. In 1978, she attended the University of Minnesota and completed her 
Bachelor of Science degree in Wildlife Management. After graduating, she worked for 
several years with the Minnesota Hennepin County Park Reserve District in the 
management and restoration of native plant and animal species. 

For four years, from 1981 to 1985, she was a Peace Corps volunteer in Honduras, 
Central America. She worked with the Honduran Department of Recursos Naturales 
Renovables on a variety of wildlife and human related issues, e.g., sport hunting of 
migratory doves, conservation of psittacines, introduction and implementation of an 
environmental education program at the primary school level, and the conservation of 
marine turtles. Since this initial exposure to sea turtles in 1981, Ms Lagueux has worked 
with four of the seven sea turtle species in four countries. 

Ms Lagueux' s interest in human use of natural resources and their conservation 
prompted her to pursue a masters degree at the University of Florida. Her research was 

214 



215 
on the use of marine turtle eggs by humans, "Olive ridley (Lepidochelys olivacea ) nesting 
in the Gulf of Fonseca and the commercialization of its eggs in Honduras." In 1989, she 
graduated with a Masters of Arts from the Center for Latin American Studies in the 
Program in Studies for Tropical Conservation at the University of Florida. Immediately 
after graduating she began working towards her doctoral degree. 

In 1 992, as a consultant to the Miskito Cays Protected Area, she began conducting 
research on human use and conservation of sea turtles in Nicaragua. She returned to 
Nicaragua in October 1993 and conducted research on the marine turtle fishery for her 
doctoral dissertation. After completing her Ph.D., Ms Lagueux will continue her research 
on human use and conservation of marine turtles on the Caribbean coast of Nicaragua as a 
Research Fellow with the Wildlife Conservation Society. Along with several colleagues 
she hopes to establish a long-term, community-based approach to the management of the 
Miskitu Indian marine turtle fishery. 



I certify that I have read this study and that in my opinion it conforms to 
acceptable standards of scholarly presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosophy. 




Kent Hteedfori, Chair 
Associate Professor of Wildlife Ecology and 
Conservation 

I certify that I have read this study and that in my opinion it conforms to 
acceptable standards of scholarly presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosophy 




LouisjrGuill 
Professor of Zoology 

I certify that I have read this study and that in my opinion it conforms to 
acceptable standards of scholarly presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosophy. 




Richard E. Bodmer 

Assistant Professor of Wildlife Ecology and 
Conservation 



I certify that I have read this study and that in my opinion it conforms to 
acceptable standards of scholarly presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosophy. 




£<-)■ <<cJ*>Pt^-4^^/ 



George W. Tanner 
Professor of Wildlife Ecology and 
Conservation 



I certify that I have read this study and that in my opinion it conforms to 
acceptable standards of scholarly presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosg 




m C. BrancF 
Associate Professor of Wildlife Ecology and 
Conservation 



I certify that I have read this study and that in my opinion it conforms to 
acceptable standards of scholarly presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosophy. 

Jeanne A. Mortimer 
Assistant Professor of Zoology 

This dissertation was submitted to the Graduate Faculty of the College of 
Agriculture and to the Graduate School and was accepted as partial fulfillment of the 
requirements for the degree of Doctor of Philosophy. ^^_^ 

May 1 998 J^^^J^M^U*^^ 

^Dean, College of Agriculture 



Dean, Graduate School 






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